Voltage difference-based capacitive touch detection device, capacitive touch detection method and capacitive touch screen panel, and display device with built-in capacitive touch screen panel

ABSTRACT

Provided is a new capacitive touch detection device, detection method, and touch screen panel for detecting a touch signal by detecting a voltage difference of a sensor pattern from a driving voltage applied by an auxiliary capacitor, and to a display device having a built-in capacitive touch screen. A capacitive touch detection device includes: a sensor pattern ( 10 ) forming a touch capacitance (Ct) in between a touch input device and the sensor pattern; an auxiliary capacitor (Caux) connected on one side to the sensor pattern ( 10 ) and having a driving voltage for touch detection applied to the other side thereof; a charging unit ( 12 ) for providing pre-charge signals to the touch capacitance (Ct) and the auxiliary capacitor (Caux); and a touch detection sensor ( 14 ) which is connected to the sensor pattern ( 10 ) and which detects a touch signal by detecting a voltage difference in the sensor pattern ( 10 ) when the touch capacitance (Ct) is added to the auxiliary capacitor (Caux) according to a touch of a touch input instrument. Effects of parasitic capacitance generated due to noise, coupling phenomena and other factors are minimized, to thus stably acquire touch signals.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/003,443 filed Sep. 5, 2013(now pending), which is a national entry ofInternational Application No. PCT/KR2012/001582, filed Mar. 2, 2012,which claims priority to Korea Patent Appl. No. 10-2011-0019867 filedMar. 7, 2011 in the Korean Intellectual Property Office, the entirecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a device, method, and touch screenpanel, for detecting a capacitive touch input of a bodily finger or atouch input instrument having conductive characteristics similar to thebodily finger, and a display device with a built-in capacitive touchscreen panel, and more particularly, to a capacitive touch detectiondevice, capacitive touch detection method, and capacitive touch screenpanel, which acquires a touch signal by detecting a voltage differencein a touch detection sensor when a driving voltage is applied through anauxiliary capacitor connected to the touch detection sensor, and adisplay device with a built-in capacitive touch screen panel.

BACKGROUND ART

Usually, touch screen panels are input devices which are respectivelyattached onto display devices such as LCDs (Liquid Crystal Displays),PDPs (Plasma Display Panels), OLED (Organic Light Emitting Diode)displays, and AMOLED (Active Matrix Organic Light Emitting Diode)displays, to thus generate an input signal corresponding to a positionwhere an object such as a finger or a touch pen is touched on the touchscreen panel. The touch screen panels are widely used in various fieldsof mobile devices such as small-sized portable mobile phones, industrialterminal devices, and DIDs (Digital Information Devices).

Various types of conventional touch screen panels are disclosed, butresistive type touch screen panels having simple manufacturing processesand inexpensive manufacturing costs have been used most widely. Theresistive type touch screen panels, however, have a low transmittanceand undergo a pressure to be applied, respectively, to thereby cause aninconvenient use. The resistive type touch screen panels also havedifficulties in recognizing multiple touches and gestures, and causedetection errors.

In contrast, capacitive touch screen panels may have a hightransmittance, recognize soft touches, and detect multiple touches andgestures satisfactorily, to thus widen a market share gradually.

FIG. 1 shows an example of the structure of a conventional capacitivetouch screen panel. Referring to FIG. 1, in the conventional capacitivetouch screen panel, transparent conductive films are respectively formedon the top and bottom surfaces of a transparent substrate 2 made ofplastic or glass. Metal electrodes 4 for applying a voltage are formedat each of four corners of the transparent substrate 2. The transparentconductive film is formed of transparent metal such as ITO (Indium TinOxide) or ATO (Antimony Tin Oxide). The metal electrodes 4 respectivelyformed at the four corners of the transparent conductive film are formedby printing low resistivity conductive metal such as silver (Ag). Aresistor network is formed around the metal electrodes 4. The resistornetwork is formed in a linearization pattern in order to transmit acontrol signal equally on the entire surface of the transparentconductive film. A protective film is coated on top of the transparentconductive film including the metal electrodes 4.

In the case of the capacitive touch screen panel, when a high-frequencyalternating-current (AC) voltage is applied to the metal electrodes 4,the high-frequency alternating-current (AC) voltage spreads to the wholesurface of the transparent substrate 2. Here, if a finger 8 or aconductive touch input unit lightly touches the top surface of thetransparent conductive film on the transparent substrate 2, a certainamount of electric current is absorbed into the human body and a changein the electric current is detected by a built-in electric currentsensor of a controller 6, to thus calculate the amount of electriccurrent at the four metal electrode 4, respectively, and to therebyrecognize a touch point.

However, the capacitive touch screen panel shown in FIG. 1 detects theamount of micro-current, and requires an expensive detecting device, tothus raise the price of the capacitive touch screen panel, and make itdifficult to detect multiple touches.

In recent years, in order to overcome such problems, the capacitivetouch screen panel shown in FIG. 2 has been chiefly used. The touchscreen panel of FIG. 2 includes a transverse linear sensor pattern 5 a,a longitudinal linear sensor pattern 5 b, and a touch drive IC(Integrated Circuit) 7 for analyzing a touch signal. The touch screenpanel detects a magnitude of a capacitance that is formed between thelinear sensor pattern 5 and the finger 8. Here, the touch screen panelscans the transverse linear sensor pattern 5 a and the longitudinallinear sensor pattern 5 b to thus detect a touch signal and to therebyrecognize a plurality of touch points.

However, when the touch screen panel is mounted on a display device suchas a liquid crystal display (LCD) and is used, it may be difficult todetect a signal due to noise. For example, the liquid crystal display(LCD) uses a common electrode and an alternating-current (AC) commonvoltage (Vcom) is applied the common electrode in some cases. The commonvoltage Vcom of the common electrode acts as noise when detecting touchpoints.

FIG. 3 shows an example in which a conventional capacitive touch screenpanel is installed on a liquid crystal display (LCD). A display device200 such as the liquid crystal display (LCD) has a structure that liquidcrystal is sealed and filled between a lower-side thin film transistor(TFT) substrate 205 and an upper-side color filter 215 to thereby form aliquid crystal layer 210. To seal the liquid crystal, the TFT substrate205 and the color filter 215 are joined by sealants 230 at their outerportions. Although they are not shown, polarizing plates are attached onthe top and bottom of the LCD panel, and besides back light units (BLUs)are provided.

As shown, a touch screen panel is provided on top of the display device200. The touch screen panel has a structure that the linear sensorpattern 5 is put on the upper surface of the substrate 1. A protectionpanel 3 for protecting the linear sensor pattern 5 is attached on top ofthe substrate 1. The touch screen panel is bonded to the outer portionof the display device 200 through the medium of an adhesive member 9such as a double adhesive tape (DAT), and an air gap 9 a is formedbetween the display device 200 and the touch screen panel.

In this configuration, if a touch occurs as shown in FIG. 3, acapacitance Ct is formed between the finger 8 and the linear sensorpattern 5. Meanwhile, as shown, a capacitance Cvcom is formed betweenthe linear sensor pattern 5 and a common electrode 220 formed on thelower surface of the color filter 215 of the display device 200, and anunknown parasitic capacitance Cp due to capacitive couplings betweenpatterns or manufacturing process factors also functions at the linearsensor pattern 5. Thus, the same circuit as an equivalent circuit ofFIG. 4 is configured.

Here, the conventional touch screen panel recognizes a touch bydetecting an amount of change in the capacitance Ct, where thebackground components such as the capacitances Cvcom and Cp act as noiseat the time of detecting the capacitance Ct. For example, small- andmedium-sized LCDs for mobile devices employ a line inversion method inwhich the common voltage Vcom of the common electrode 220 alternates byone or a plurality of gate lines as shown in FIG. 5, in order to reducecurrent consumption, and thus the alternating electric field acts asconsiderable noise at the time of detection of touches.

Typically, in order to remove the noise, the air gap 9 a is placedbetween the touch screen panel and the display device 200 as shown inFIG. 3. In addition, although it is not shown, an ITO layer is coated onthe lower surface of the substrate 1 of the touch-screen panel, tothereby form a shield layer. In addition, the shield layer is groundedwith the ground signal.

However, in the case of the conventional art, products become thick andthe quality of the products deteriorates due to the air gap 9 a. Inaddition, the conventional art requires a separate shield layer and amanufacturing process of configuring the shield layer, thereby causing arise of a manufacturing cost. In particular, in the case of forming abuilt-in touch screen panel in a liquid crystal display (LCD), it isvery difficult to form the air gap 9 a or the shield layer, and thus itis also very difficult to form the built-in touch screen panel in adisplay device such as the liquid crystal display (LCD).

DISCLOSURE Technical Problem

In order to solve the above-mentioned problems of a conventionalcapacitive touch screen panel, it is an object of the present inventionto provide a capacitive touch detection device, capacitive touchdetection method, and capacitive touch screen panel, which acquires atouch signal by detecting a voltage difference that causes a differencebetween voltages in magnitude that are detected from a touch detectionsensor according to a magnitude of a touch capacitance, when anauxiliary capacitor is connected to the touch detection sensor, adriving voltage is applied through the auxiliary capacitor, and thetouch capacitance is additionally formed between a touch inputinstrument and a sensor pattern, and a display device with a built-incapacitive touch screen panel, to thereby minimize an influence due tonoise of a common electrode of the display device, and an influence dueto a parasitic capacitance, to thereby stably acquire the touch signal,and to thereby simultaneously facilitate to incorporate a built-in touchscreen panel in the display device such as a liquid crystal display(LCD).

Technical Solution

To attain the above object of the present invention, according to anaspect of the present invention, there is provided a capacitive touchdetection device for detecting occurrence of a touch capacitance (Ct) byan approach of a bodily finger (25) or a touch input instrument such asa conductor similar to the bodily finger, the capacitive touch detectiondevice comprising: at least one sensor pattern (10) that forms the touchcapacitance (Ct) between the touch input instrument and the sensorpattern; an auxiliary capacitor (Caux) whose one side is connected tothe sensor pattern (10) and to the other side of which a driving voltagefor detection of a touch input is applied; a charging unit (12) thatsupplies a pre-charge signal to the sensor pattern (10) and theauxiliary capacitor (Caux), to thus accumulate charges in the touchcapacitance (Ct) and the auxiliary capacitor (Caux); and a touchdetection sensor (14) that is connected to the sensor pattern (10), andthat detects a voltage difference that is a difference in the magnitudeof a voltage generated in the sensor pattern (10) by a driving voltageapplied to the auxiliary capacitor (Caux) when the touch capacitance(Ct) is added at the time of occurrence of a touch input, in comparisonwith the magnitude of a voltage generated by a driving voltage appliedto the auxiliary capacitor (Caux) in the sensor pattern (10) at the timeof non-occurrence of a touch input, to thereby detect a touch signal.

According to an embodiment of the present invention, the charging unit(12) is a three-terminal type switching device.

According to another embodiment of the present invention, the other sideof the auxiliary capacitor (Caux) is connected to an ON/OFF controlterminal of the charging unit (12), and the driving voltage that isapplied to the other side of the auxiliary capacitor (Caux) is the sameas an ON/OFF control voltage of the charging unit (12).

According to another embodiment of the present invention, the drivingvoltage that is applied to the other side of the auxiliary capacitor(Caux) is an alternating voltage that alternates at a predeterminedfrequency.

According to another embodiment of the present invention, the touchdetection sensor (14) detects a voltage difference in the sensor pattern(10) at a rising time and/or a falling time of the driving voltage thatis applied to the auxiliary capacitor (Caux).

According to another embodiment of the present invention, a commonelectrode capacitance (Cvcom) is formed between the sensor pattern (10)and a common electrode (220) of a display device (200), and thecapacitive touch detection device further comprises a common voltagedetector (43) that detects a common voltage level of the commonelectrode (220).

According to another embodiment of the present invention, the commonvoltage detector (43) detects a voltage difference in the sensor pattern(10) due to the common electrode capacitance (Cvcom) to thus detect arising time and a falling time of the common voltage level.

According to another embodiment of the present invention, a commonelectrode capacitance (Cvcom) is formed between the sensor pattern (10)and a common electrode (220) of a display device (200), and thecapacitive touch detection device further comprises a common voltageinformation receiver (45) that receives common voltage information ofthe common electrode (220) from the display device (200).

According to another embodiment of the present invention, the touchdetection sensor (14) detects the touch signal at a portion other than arising edge and a falling edge of the common voltage level.

According to another embodiment of the present invention, the touchdetection sensor (14) detects a voltage difference that is a differencein the magnitude of a voltage generated in the sensor pattern (10) whenthe touch capacitance (Ct) is added at the time of occurrence of a touchinput, in comparison with the magnitude of a voltage generated by theauxiliary capacitor (Caux) in the sensor pattern (10) at the time ofnon-occurrence of a touch input, to thereby detect a touch signal.

According to another embodiment of the present invention, a voltagegenerated in the sensor pattern (10) by a driving voltage applied to theauxiliary capacitor (Caux) at the time of non-occurrence of a touchinput is determined by following Equation 1, a voltage generated in thesensor pattern (10) by a driving voltage applied to the auxiliarycapacitor (Caux) at the time of addition of the touch capacitance (Ct)is determined by following Equation 2, and the voltage difference occursdue to a difference between the voltages of the following Equations 1and 2,

$\begin{matrix}{{\Delta \; {Vsensor}} = {{\pm \left( {{Vh} - {V\; l}} \right)}\frac{Caux}{{Caux} + {Cvcom} + {Cp}}}} & 1 \\{{{\Delta \; {Vsensor}} = {{\pm \left( {{Vh} - {V\; l}} \right)}\frac{Caux}{{Caux} + {Cvcom} + {Cp} + {Ct}}}},} & 2\end{matrix}$

-   -   in which ΔVsensor is a voltage difference in the sensor pattern,        Vh is a high level voltage applied to the auxiliary capacitor,        Vl is a low level voltage applied to the auxiliary capacitor,        Caux is an auxiliary capacitor capacitance, Cvcom, is a common        electrode capacitance, Cp is a parasitic capacitance, and Ct is        a touch capacitance.

According to another embodiment of the present invention, an input endof the touch detection sensor (14) is in a high-impedance state of atleast 1 Mohm at the time of detection of the touch signal.

According to another embodiment of the present invention, the touchdetection sensor (14) detects a touch sharing ratio of the touch inputinstrument with respect to the sensor pattern (10) in response to themagnitude of the voltage difference.

According to another embodiment of the present invention, the touchdetection sensor (14) is an analog-to-digital converter (ADC).

According to another embodiment of the present invention, the touchdetection sensor (14) comprises an amplifier (18) that amplifies thesignal from the sensor pattern (10).

According to another embodiment of the present invention, the amplifier(18) is a differential amplifier (18 a) that differentially amplifiesthe signal from the sensor pattern (10).

According to another embodiment of the present invention, the capacitivetouch detection device further comprises a memory unit (28) that storesthe output of the amplifier (18) for each sensor pattern (10) at thetime of non-occurrence of a touch unit, wherein it is judged whether ornot a touch input exists for each sensor pattern (10), with reference tothe memory unit (28).

According to another aspect of the present invention, there is alsoprovided a capacitive touch detection method for detecting occurrence ofa touch capacitance (Ct) by an approach of a bodily finger (25) or atouch input instrument such as a conductor similar to the bodily finger,the capacitive touch detection method comprising the steps of: (a)supplying a pre-charge signal to at least one sensor pattern (10) thatforms the touch capacitance (Ct) between the touch input instrument andthe sensor pattern (10) and an auxiliary capacitor (Caux) whose one sideis connected to the sensor pattern (10) and to the other side of which adriving voltage for detection of a touch input is applied; (b) detectinga voltage difference in the sensor pattern (10); and (c) detectingoccurrence of a voltage difference in the sensor pattern (10), tothereby detect a touch signal.

According to another embodiment of the present invention, the chargingunit (12) is a three-terminal type switching device.

According to another embodiment of the present invention, the other sideof the auxiliary capacitor (Caux) is connected to an ON/OFF controlterminal of the charging unit (12), and the driving voltage that isapplied to the other side of the auxiliary capacitor (Caux) is the sameas an ON/OFF control voltage of the charging unit (12).

According to another embodiment of the present invention, the drivingvoltage that is applied to the other side of the auxiliary capacitor(Caux) is an alternating voltage that alternates at a predeterminedfrequency.

According to another embodiment of the present invention, at step (b), avoltage difference is detected in the sensor pattern 10 at a rising timeand/or a falling time of the driving voltage that is applied to theauxiliary capacitor (Caux).

According to another embodiment of the present invention, a commonelectrode capacitance (Cvcom) is formed between the sensor pattern (10)and a common electrode (220) of a display device (200), and thecapacitive touch detection method further comprises the step ofdetecting a common voltage level of the common electrode (220).

According to another embodiment of the present invention, at the step ofdetecting a common voltage level, a voltage difference is detected inthe sensor pattern 10 due to the common electrode capacitance (Cvcom) tothus detect a rising time and a falling time of the common voltagelevel.

According to another embodiment of the present invention, a commonelectrode capacitance (Cvcom) is formed between the sensor pattern (10)and a common electrode (220) of a display device (200), and thecapacitive touch detection method further comprises the step ofreceiving common voltage information of the common electrode (220) fromthe display device (200).

According to another embodiment of the present invention, at step (c),the touch signal is detected at a portion other than a rising edge and afalling edge of the common voltage level.

According to another embodiment of the present invention, at step (c), avoltage difference that is a difference in the magnitude of a voltagegenerated in the sensor pattern (10) when the touch capacitance (Ct) isadded at the time of occurrence of a touch input, is detected incomparison with the magnitude of a voltage generated by the auxiliarycapacitor (Caux) in the sensor pattern (10) at the time ofnon-occurrence of a touch input, to thereby detect a touch signal.

According to another embodiment of the present invention, a voltagegenerated in the sensor pattern (10) by a driving voltage applied to theauxiliary capacitor (Caux) at the time of non-occurrence of a touchinput is determined by following Equation 1, a voltage generated in thesensor pattern (10) by a driving voltage applied to the auxiliarycapacitor (Caux) at the time of addition of the touch capacitance (Ct)is determined by following Equation 2, and the voltage difference occursdue to a difference between the voltages of the following Equations 1and 2,

$\begin{matrix}{{\Delta \; {Vsensor}} = {{\pm \left( {{Vh} - {V\; l}} \right)}\frac{Caux}{{Caux} + {Cvcom} + {Cp}}}} & 1 \\{{{\Delta \; {Vsensor}} = {{\pm \left( {{Vh} - {V\; l}} \right)}\frac{Caux}{{Caux} + {Cvcom} + {Cp} + {Ct}}}},} & 2\end{matrix}$

-   -   in which ΔVsensor is a voltage difference in the sensor pattern,        Vh is a high level voltage applied to the auxiliary capacitor,        Vl is a low level voltage applied to the auxiliary capacitor,        Caux is an auxiliary capacitor capacitance, Cvcom is a common        electrode capacitance, Cp is a parasitic capacitance, and Ct is        a touch capacitance.

According to another embodiment of the present invention, at step (c),an input end of a portion of detecting the touch signal is in ahigh-impedance state of at least 1 Mohm at the time of detection of thetouch signal.

According to another embodiment of the present invention, at step (c), atouch sharing ratio of the touch input instrument with respect to thesensor pattern (10) is detected in response to the magnitude of thevoltage difference.

According to another embodiment of the present invention, at step (c),it is detected whether or not a voltage difference is detected in thesensor pattern (10) by using an analog-to-digital converter (ADC).

According to another embodiment of the present invention, at step (c),it is detected whether or not a voltage difference is detected in thesensor pattern (10) by using an amplifier (18) that amplifies the signalfrom the sensor pattern (10).

According to another embodiment of the present invention, the amplifier(18) is a differential amplifier (18 a) that differentially amplifiesthe signal from the sensor pattern (10).

According to another embodiment of the present invention, the capacitivetouch detection method further comprises the step of storing the outputof the amplifier (18) in a memory unit (28) for each sensor pattern (10)at the time of non-occurrence of a touch unit, wherein at step (c), itis detected whether or not a voltage difference is detected in thesensor pattern (10), for each sensor pattern (10) with reference to thememory unit (28).

According to another aspect of the present invention, there is alsoprovided a capacitive touch screen panel for detecting occurrence of atouch capacitance (Ct) by an approach of a bodily finger (25) or a touchinput instrument such as a conductor similar to the bodily finger, thecapacitive touch screen panel comprising: a substrate (50); at least onesensor pattern (10) that is formed on top of the substrate (50), andforms the touch capacitance (Ct) between the touch input instrument andthe sensor pattern; an auxiliary capacitor (Caux) whose one side isconnected to the sensor pattern (10) and to the other side of which adriving voltage for detection of a touch input is applied; a chargingunit (12) that supplies a pre-charge signal to the sensor pattern (10)and the auxiliary capacitor (Caux), to thus accumulate charges in thetouch capacitance (Ct) and the auxiliary capacitor (Caux); a touchdetection sensor (14) that is connected to the sensor pattern (10), andthat detects a voltage difference that is a difference in the magnitudeof a voltage generated in the sensor pattern (10) by a driving voltageapplied to the auxiliary capacitor (Caux) when the touch capacitance(Ct) is added at the time of occurrence of a touch input, in comparisonwith the magnitude of a voltage generated by a driving voltage appliedto the auxiliary capacitor (Caux) in the sensor pattern (10) at the timeof non-occurrence of a touch input, to thereby detect a touch signal;and a drive integrated circuit (IC) (30) that controls the charging unit(12) to supply a pre-charge signal to the touch capacitance (Ct) andcomputes touch coordinates from the output of the touch detection sensor(14).

According to another embodiment of the present invention, the chargingunit (12) is a three-terminal type switching device.

According to another embodiment of the present invention, the other sideof the auxiliary capacitor (Caux) is connected to an ON/OFF controlterminal of the charging unit (12), and the driving voltage that isapplied to the other side of the auxiliary capacitor (Caux) is the sameas an ON/OFF control voltage of the charging unit (12).

According to another embodiment of the present invention, the drivingvoltage that is applied to the other side of the auxiliary capacitor(Caux) is an alternating voltage that alternates at a predeterminedfrequency.

According to another embodiment of the present invention, the touchdetection sensor (14) detects a voltage difference in the sensor pattern(10) at a rising time and/or a falling time of the driving voltage thatis applied to the auxiliary capacitor (Caux).

According to another embodiment of the present invention, a commonelectrode capacitance (Cvcom) is formed between the sensor pattern (10)and a common electrode (220) of a display device (200), and thecapacitive touch screen panel further comprises a common voltagedetector (43) that detects a common voltage level of the commonelectrode (220).

According to another embodiment of the present invention, the commonvoltage detector (43) detects a voltage difference in the sensor pattern10 due to the common electrode capacitance (Cvcom) to thus detect arising time and a falling time of the common voltage level.

According to another embodiment of the present invention, a commonelectrode capacitance (Cvcom) is formed between the sensor pattern (10)and a common electrode (220) of a display device (200), and thecapacitive touch screen panel further comprises a common voltageinformation receiver (45) that receives common voltage information ofthe common electrode (220) from the display device (200).

According to another embodiment of the present invention, the touchdetection sensor (14) detects the touch signal at a portion other than arising edge and a falling edge of the common voltage level.

According to another embodiment of the present invention, the touchdetection sensor (14) detects a voltage difference that is a differencein the magnitude of a voltage generated in the sensor pattern (10) whenthe touch capacitance (Ct) is added at the time of occurrence of a touchinput, in comparison with the magnitude of a voltage generated by theauxiliary capacitor (Caux) in the sensor pattern (10) at the time ofnon-occurrence of a touch input, to thereby detect a touch signal.

According to another embodiment of the present invention, a voltagegenerated in the sensor pattern (10) by a driving voltage applied to theauxiliary capacitor (Caux) at the time of non-occurrence of a touchinput is determined by following Equation 1, a voltage generated in thesensor pattern (10) by a driving voltage applied to the auxiliarycapacitor (Caux) at the time of addition of the touch capacitance (Ct)is determined by following Equation 2, and the voltage difference occursdue to a difference between the voltages of the following Equations 1and 2,

$\begin{matrix}{{\Delta \; {Vsensor}} = {{\pm \left( {{Vh} - {V\; l}} \right)}\frac{Caux}{{Caux} + {Cvcom} + {Cp}}}} & 1 \\{{{\Delta \; {Vsensor}} = {{\pm \left( {{Vh} - {V\; l}} \right)}\frac{Caux}{{Caux} + {Cvcom} + {Cp} + {Ct}}}},} & 2\end{matrix}$

-   -   in which ΔVsensor is a voltage difference in the sensor pattern,        Vh is a high level voltage applied to the auxiliary capacitor,        Vl is a low level voltage applied to the auxiliary capacitor,        Caux is an auxiliary capacitor capacitance, Cvcom is a common        electrode capacitance, Cp is a parasitic capacitance, and Ct is        a touch capacitance.

According to another embodiment of the present invention, an input endof the touch detection sensor (14) is in a high-impedance state of atleast 1 Mohm at the time of detection of the touch signal.

According to another embodiment of the present invention, the touchdetection sensor (14) detects a touch sharing ratio of the touch inputinstrument with respect to the sensor pattern (10) in response to themagnitude of the voltage difference.

According to another embodiment of the present invention, the touchdetection sensor (14) is an analog-to-digital converter (ADC).

According to another embodiment of the present invention, the touchdetection sensor (14) comprises an amplifier (18) that amplifies thesignal from the sensor pattern (10).

According to another embodiment of the present invention, the amplifier(18) is a differential amplifier (18 a) that differentially amplifiesthe signal from the sensor pattern (10).

According to another embodiment of the present invention, the capacitivetouch screen panel further comprises a memory unit (28) that stores theoutput of the amplifier (18) for each sensor pattern (10) at the time ofnon-occurrence of a touch unit, wherein it is judged whether or not atouch input exists for each sensor pattern (10), with reference to thememory unit (28).

According to another embodiment of the present invention, a plurality ofthe sensor patterns (10) are arranged in a dot matrix form, in an activeregion (90) of the substrate (50), and the charging unit (12) and thetouch detection sensor (14) are provided for each sensor pattern (10).

According to another embodiment of the present invention, a plurality ofthe sensor patterns (10) are arranged in a dot matrix form, in an activeregion (90) of the substrate (50), and the charging unit (12) and thetouch detection sensor (14) are assigned for the plurality of the sensorpatterns (10) and used by multiplexing the plurality of the sensorpatterns (10).

According to another embodiment of the present invention, the chargingunit (12) and the touch detection sensor (14) are provided in anon-visible region (92) of the substrate (50).

According to another embodiment of the present invention, the chargingunit (12) and the touch detection sensor (14) are integrated in thedrive IC (30).

According to another embodiment of the present invention, a plurality ofthe sensor patterns (10) are arranged in a linear form in an activeregion (90) of the substrate (50), and cross sections (42) at which atleast two or more linear sensor patterns (10 a, 10 b) intersect areformed.

According to another embodiment of the present invention, the linearsensor patterns (10 a, 10 b) comprise opposite areas (41 a) that formtouch capacitance (Ct) between each of the sensor patterns (10 a, 10 b)and the touch input instrument, and connectors (41 b) that connect theopposite areas (41 a).

According to another embodiment of the present invention, the chargingunit (12) and the touch detection sensor (14) that are assigned to eachof the linear sensor patterns (10 a, 10 b) are provided in a non-visibleregion (92) of the substrate (50).

According to another embodiment of the present invention, the chargingunit (12) and the touch detection sensor (14) that are assigned to eachof the linear sensor patterns (10 a, 10 b) are integrated in the driveIC (30).

According to another embodiment of the present invention, a sensorsignal line (22) withdrawn from the sensor pattern (10) is wired by atransparent signal line in at least an active region (90) of thesubstrate (50).

According to another embodiment of the present invention, the sensorsignal line (22) is wired into a metal signal line (22 b) that isconnected with the transparent signal line (22 a) by the medium of aconnector (59) in the non-visible region (92) of the substrate (50).

According to another embodiment of the present invention, the sensorsignal lines (22) are placed between the sensor patterns (10) in theactive region (90) of the substrate (50).

According to another embodiment of the present invention, the line widthof the sensor signal line (22) varies depending on the location of thesensor pattern (10) on the substrate (50).

According to another embodiment of the present invention, the drive IC(30) is mounted in a COG (Chip On Glass) or COF (Chip On Film) form atone side of the substrate (50).

According to another embodiment of the present invention, a plurality ofdrive ICs (30) are mounted at one side of the substrate (50), in whichone is a master drive IC (30 a) that transfers touch signals to theoutside, and the others are slave drive ICs (30 b) that communicate withthe master drive IC (30 a).

According to another embodiment of the present invention, the masterdrive IC (30 a) and the slave drive ICs (30 b) refer to mutual touchdetection information on the boundary surface of regions that govern themaster drive IC (30 a) and the slave drive ICs (30 b).

According to another embodiment of the present invention, a protectionpanel (52) is further attached on top of the substrate (50).

According to another embodiment of the present invention, the substrate(50) is built in a display device (200), or is any one of substratesconstituting the display device (200).

According to another aspect of the present invention, there is alsoprovided a display device with a built-in capacitive touch screen panelwherein the built-in capacitive touch screen panel is a capacitive touchscreen panel according the ones mentioned above, and any one substrateof a basic structure has a structure of the substrate (50).

According to another embodiment of the present invention, the displaydevice (200) is a liquid crystal display device, and the substrate (50)is a color filter (215) of the display device.

According to another embodiment of the present invention, the drive IC(60) for displaying and the drive IC (30) for the touch screen panel areintegrated into a single IC.

According to another embodiment of the present invention, the sensorpattern (10) is located on the boundary surface that discriminatespixels.

According to another embodiment of the present invention, the sensorpattern (10) is formed to avoid invading a pixel area.

According to another embodiment of the present invention, the sensorsignal line (22) withdrawn from the sensor pattern (10) is placed alongthe boundary surface that discriminates pixels.

According to another embodiment of the present invention, the sensorpattern (10) and the sensor signal line (22) are formed by a same mask.

According to another embodiment of the present invention, the sensorpattern (10) and the sensor signal line (22) are formed of metal.

According to another embodiment of the present invention, the sensorpattern (10) is formed between the color resin and the glass of a colorfilter (215).

Advantageous Effects

In the case that a common electrode of a display device has a commonvoltage level alternating at a predetermined frequency, the commonelectrode of the display device has a direct-current (DC) level, or thecommon electrode of the display device alternates at an unqualifiedunspecified frequency, a voltage difference-based capacitive touchdetection device, capacitive touch detection method, and capacitivetouch screen panel, and a display device with a built-in capacitivetouch screen panel, according to the present invention, detects changesin the state of a common voltage, avoids a point in time of the changesof the state, applies a driving voltage through an auxiliary capacitorconnected to a touch detection sensor, and detects occurrence of avoltage difference in the touch detection sensor by a touch capacitanceadded by a touch input, to thereby acquire a touch signal. As a result,influences due to a parasitic capacitance generated by noise, a couplingphenomenon, or other factors are minimized, and erroneous recognition ofsignals does not occur. In addition, the present invention detects atouch input at a relatively high voltage level, to thus easily capture asignal even with a small cross-sectional area of a touch inputinstrument, and to thereby make it possible to perform a stylus peninput. In addition, the present invention obtains a touch share ratio ofa touch input instrument depending on the magnitude of a voltagedifference, to thus increase touch resolution and enable finehandwriting and drawing. In addition, the present invention mayconfigure an active region of a touch screen panel into a single-layer,to thus simplify a manufacturing process and provide an effect ofobtaining an excellent yield.

DESCRIPTION OF DRAWINGS

The above and other objects and advantages of the invention will becomemore apparent by describing the preferred embodiments with reference tothe accompanying drawings in which:

FIG. 1 is a perspective view showing an example of a conventionalcapacitive touch screen panel;

FIG. 2 is a plan view showing another example of a conventionalcapacitive touch screen panel;

FIG. 3 is a cross-sectional view showing an example in which a touchscreen panel of FIG. 2 is installed on top of a display device;

FIG. 4 is an equivalent circuit diagram showing that a touch capacitanceis detected in FIG. 3;

FIG. 5 is a waveform diagram illustrating a common voltage waveform of aliquid crystal display device;

FIG. 6 is a diagram conceptually showing a conventional three-terminaltype switching device;

FIG. 7 is a conceptual view depicting a principle of detecting a touchinput;

FIG. 8 is a circuit diagram illustrating a basic structure of a touchdetection device according to an embodiment of the present invention;

FIG. 9 is a circuit diagram illustrating a touch detection deviceaccording to another embodiment of the present invention;

FIG. 10 is a cross-sectional view showing a configuration of sensorpatterns according to an embodiment of the present invention;

FIG. 11 is a cross-sectional view showing a configuration of sensorpatterns according to another embodiment of the present invention;

FIG. 12 is a circuit diagram illustrating a touch detection deviceaccording to still another embodiment of the present invention;

FIG. 13 is a waveform diagram illustrating a process of detecting atouch signal in the present invention;

FIG. 14 is a schematic block diagram showing an example of a memoryunit;

FIG. 15 is a schematic diagram showing a touch screen panel according toan embodiment of the present invention;

FIG. 16 is a schematic diagram showing a touch screen panel according toanother embodiment of the present invention;

FIG. 17 is a plan view showing an example in which a plurality of driveintegrated circuits (ICs) are provided;

FIG. 18 is a schematic diagram showing a touch screen panel according tostill another embodiment of the present invention;

FIG. 19 is a plan view showing a configuration of a thin film transistor(TFT) substrate of a liquid crystal display (LCD) device;

FIG. 20 is a cross-sectional view showing a display device having abuilt-in touch screen panel according to the present invention; and

FIG. 21 is a disassembled perspective view illustrating a display devicehaving a built-in touch screen panel according to the present invention;and

FIG. 22 is a cross-sectional view showing a configuration of sensorpatterns according to still another embodiment of the present invention.

BEST MODE

Hereinbelow, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

First, the present invention relates to a voltage difference-basedcapacitive touch detection device, capacitive touch detection method,and capacitive touch screen panel, and a display device with a built-incapacitive touch screen panel. A conventional capacitive touch detectiondevice detects a change in capacitance due to contact of a finger andthe like, but the capacitive touch detection device according to thepresent invention detects a voltage difference caused by a correlationof the magnitude of a touch capacitance due to an auxiliary capacitorand each of sensor patterns, when an alternating driving voltage isapplied to the added auxiliary capacitor. A touch detecting systemaccording to the present invention compares a voltage due to anauxiliary capacitor, a common electrode capacitance, and a parasiticcapacitance at the time of non-occurrence of a touch input, with avoltage that is generated when a touch capacitance is added to thecommon electrode capacitance at the time of occurrence of a touch input,and thus detects a voltage difference that is a difference in magnitudesbetween the two voltages, to thus minimize influences caused by externalnoise or a parasitic capacitance, and to thereby acquire a touch signalmore reliably.

The display devices referred to in the present invention, may be LCDs(Liquid Crystal Displays), PDPs (Plasma Display Panels), OLED (OrganicLight Emitting Diode) displays, and AMOLED (Active Matrix Organic LightEmitting Diode) displays, or any other means of displaying imagesthereon. LCDs (Liquid Crystal Displays) of the above-listed displaydevices need a common voltage (Vcom) for operation of liquid crystals.As an example, small and medium-sized LCDs for mobile devices employline inversion methods in which a common voltage of a common electrodealternates for one or a plurality of gate lines, to reduce the currentconsumption. As another example, large-sized LCDs are configured so thata common voltage of a common electrode has a constant DC level. As stillanother example, a certain display device is configured to form ashielding electrode that acts as being common for the entire panel toshut off the external electrostatic discharge (ESD), and to make theshielding electrode grounded into the ground signal. Otherwise, in anytransverse electric field mode LCDs, a common electrode is located onthe TFT substrate, and the common voltage that is detected from theupper surface of a color filter is configured to alternate at anunspecified frequency up and down based on the DC level.

In the present invention, in addition to the electrodes to which theabove common voltage (Vcom) is applied, all the electrodes playing acommon role in a display device are referred to as “common electrodes”and an alternating voltage or a DC voltage or a voltage alternating atan unspecified frequency is referred to as a “common voltage.”

The present invention detects a non-contact touch input of a finger or atouch input instrument having electrical characteristics similar to thefinger. Here, the term “non-contact touch input” means that a touchinput instrument of a finger and the like performs a touch input at astate spaced by a predetermined distance apart from a sensor pattern bya substrate. The touch input instrument may contact an outer surface ofthe substrate. However, even in this case, the touch input instrumentand the sensor pattern remain in a non-contact state. Therefore, a touchaction of a finger on a sensor pattern may be expressed in the term“approach.” Meanwhile, since a finger remains in a contact state for anouter surface of the substrate, a touch action of a finger on thesubstrate may be expressed in the term “contact.” In this specificationand claims, the terms “approach” and “contact” are commonly used as thesame meanings as above.

The components such as “˜ portion” are configurational elements thatperform certain functions and mean software configurational elements orhardware configurational elements such as FPGA (Field-Programmable GateArray) or ASIC (Application Specific Integrated Circuit). In addition,the software or hardware configurational elements can be included inlarger components or can include smaller components. In addition, thesoftware or hardware configurational elements may contain their owncentral processing units (CPUs) therein.

In the following drawings, thickness or areas have been enlarged todefinitely show several layers and areas. Through the whole detaileddescription of the specification, like reference numerals are used forlike elements. When it is mentioned that a portion such as a layer, afilm, an area and a substrate is placed “on” or “on the upper surface”of another portion, this means that the portion is not only placed“justly on” the other portion but also the former is placed on a thirdportion between the former and the latter. In contrary, when it ismentioned that a certain portion is placed “justly on” another portion,this means that there are no other portions between them. In addition,the signal described herein, collectively refer to, unless otherwisestated, voltage or current.

FIG. 6 is a conceptual diagram showing a three-terminal type switchingdevice that is used as an example of a charging unit in the presentinvention. Referring to FIG. 6, the three-terminal type switching deviceincludes three terminals having an ON/OFF control terminal (indicated as“Cont” in FIG. 6), an input terminal (indicated as “In” in FIG. 6), andan output terminal (indicated as “Out” in FIG. 6). The ON/OFF controlterminal is a control terminal for controlling the ON/OFF operations ofthe switching device. If a predetermined magnitude of voltage or currentis applied to the ON/OFF control terminal, voltage or current that isapplied to the input terminal is output in the form of voltage orcurrent via the output terminal.

The three-terminal type switching device referred to as the chargingunit in the present invention may be for example, a relay, a MOS (MetalOxide Semiconductor) switch, a BJT (Bipolar Junction Transistor) switch,a FET (Field Effect Transistor) switch, a MOSFET (Metal OxideSemiconductor Field Effect Transistor) switch, an IGBT (Insulated GateBipolar Transistor) switch, a TFT (Thin Film Transistor) switch, or anOP-AMP (OPerational AMPlifier) switch, and may be formed by ahomogeneous or heterogeneous combination among these.

The relay may be used as a four-terminal type switching device, inaddition to the three-terminal type switching device. All devices havingan ON/OFF control terminal that turns on/off an input and outputregardless of the number of input and output terminals and whose inputand output are turned on/off by the ON/OFF control terminal, may be usedas the charging unit.

Meanwhile, a CMOS (Complementary Metal Oxide Semiconductor) switch isformed by a mutual combination of PMOS (P-channel MOS) and NMOS(N-channel MOS) switches as an example of the three-terminal typeswitching device, in which input and output terminals are connected toeach other, but the ON/OFF control terminal exists separately and isconnected to an identical control signal, or is connected separately toindividual control signals, to thus determine an ON/OFF state of theswitch. The relay is a device that when a current is applied to acontrol terminal, a voltage or current applied to the input terminal isoutput without loss. The BJT switch is a device in which a certainamount of amplified current flows from a collector terminal thereof toan emitter terminal thereof when a current is applied to a base terminalthereof at a state where a current higher than a threshold voltage ofthe base terminal has been applied to the base terminal. In addition,the TFT switch is a switching device that is used in a pixel unit fordisplay device such as a LCD or AMOLED, and includes a gate terminalthat is a control terminal, a source terminal that is an input terminal,and a drain terminal that is an output terminal, in which the TFT switchis energized when a voltage higher than a threshold voltage higher thana voltage applied to the drain terminal is applied to the gate terminal,and thus a current depending on the magnitude of a voltage applied tothe gate terminal flows from the input terminal to the output terminal.

Prior to describing embodiments of the present invention, a principlethat detects a touch input in the present invention will be describedbriefly with reference to FIG. 7. As shown in FIG. 7, it is assumed thatwhen a finger 25 or a conductive touch unit similar to the fingerapproaches to a sensor pad 10, a distance between the finger 25 and thesensor pad 10 is an interval “d” and an opposite area is “A.” Anelectrostatic capacitance “C” is formed between the finger 25 and thesensor pad 10 as shown in a right-side equivalent circuit of FIG. 7 anda numerical formula. If a voltage or current signal is applied to asignal input line of the sensor pad 10 having the electrostaticcapacitance “C,” charges of a magnitude “Q” are accumulated and avoltage relationship formula is formed as V=Q/C. As a result, theelectrostatic capacitance “C” accumulates the charges “Q.” In thepresent invention, when a voltage difference having a correlation withrespect to the magnitude of the electrostatic capacitance “C” occurs inthe sensor pattern 10 connected with the touch detection sensor, a touchinput is detected by using the detected voltage difference.

FIG. 8 is a circuit diagram illustrating a basic structure of a touchdetection device according to the present invention. Referring to FIG.8, the touch detection device according to the present invention has abasic structure including a charging unit 12, a sensor pattern 10, asensor signal line 22, an auxiliary capacitor Caux, and a touchdetection sensor 14.

In FIG. 8, the charging unit 12 is a unit for supplying a pre-chargesignal to the sensor pattern 10, in which the pre-charge signal is avoltage that is applied to all capacitors connected to the touchdetection sensor 14 as a constant DC voltage to charge the capacitors,prior to detecting touch inputs. Thus, the charging unit 12 is aswitching device that performs a switching operation according to acontrol signal supplied to the ON/OFF control terminal, or a lineardevice such as an OP-AMP that supplies a signal based on a controlsignal. As shown, when a three-terminal type switching device is used asthe charging unit 12, a proper charging voltage may be supplied to thesensor pattern 10 at a required point in time by using a control signalsupplied to the ON/OFF control terminal and a signal fed to the inputterminal. A DC voltage including zero V, or an alternating AC voltagesuch as square, triangular or sinusoidal waves, may be used as thecharging voltage.

The sensor pattern 10 is formed of a transparent conductor or metal. Inthe case that the sensor pattern 10 is mounted on a display device andis formed as a transparent conductor, the transparent conductor isformed of a transparent conductive material, such as ITO (Indium TinOxide), ATO (Antimony Tin Oxide), CNT (Carbon Nano Tube), or IZO (IndiumZinc Oxide) or a transparent material with conductive characteristicssimilar to the ITO, ATO, CNT, or IZO. In the case that the sensorpattern 10 is not mounted on the display device, but is applied as atouch keyboard or a touch key pad that is used for a refrigerator ormonitor, the sensor pattern 10 may be formed of a non-transmissivematerial such as metal.

The sensor pattern 10 may be patterned in various forms. For example,the sensor pattern 10 may be arranged in a dot-matrix form in whichisolated islands are arranged in a matrix form in an active region of asubstrate 50, or the sensor pattern 10 may be arranged so that linearpatterns are arranged lengthwise and crosswise on the substrate 50. Aform of the sensor pattern 10 will be described in an embodiment to bedescribed later.

The sensor signal line 22 is a signal line for detecting the presence ofa touch input when a finger 25 or a touch unit (for example, such as acapacitive touch pen) having a conductive characteristic similar to thatof the finger 25 approaches the sensor pattern 10. The sensor signalline 22 is a signal line that connects the sensor pattern 10 and thetouch detection sensor 14, and may be formed of the same conductivetransparent material as that of the sensor pattern 10. However, in somecases, the sensor signal line 22 may be formed of a non-transmissivematerial such as metal. The specific embodiments of the sensor signalline 22 will be described later.

The auxiliary capacitor (Caux) is an element to which a driving voltageis applied for detection of a touch input in the present invention, inwhich one end of the auxiliary capacitor (Caux) is connected to thetouch detection sensor 14, and to the other end of which a drivingvoltage is applied. Here, the reference characters “Caux” is a symbolthat represents both the name and magnitude of a capacitor. For example,the symbol “Caux” means a capacitor named Caux and simultaneously meansa capacitance having Caux in magnitude. Other capacitor symbols such asCt, Cvcom and Cp to be described later represents both the names andmagnitudes of the capacitors.

As illustrated, the output terminal (Out) of the charging unit 12 isconnected to the touch detection sensor 14. In addition, one end of theauxiliary capacitor (Caux) is connected to the output terminal (Out) ofthe charging unit 12, and a driving voltage is applied to the other endof the auxiliary capacitor (Caux). The drive signal is an alternatingvoltage, and is a periodic or non-periodic waveform such as a square,sinusoidal, or triangular wave. A voltage that is proportional to thesize of the alternating driving voltage is derived and detected from thetouch detection sensor 14 or the sensor pattern 10. The voltage isdetected at the connecting point between the touch detection sensor 14and the sensor pattern 10. Accordingly, the expression that a signal isdetected at the sensor pattern 10 or at the touch detection sensor 14means that the signal is detected at the connecting point between thesensor pattern 10 and the touch detection sensor 14 throughout thisspecification.

FIG. 9 shows an embodiment of the switching device in which a MOS (MetalOxide Semiconductor) or FET (Field Effect Transistor) switch is used,and an Analog to Digital Converter (ADC) is used as an embodiment of thetouch detection sensor 14. The ADC 14 a converts detected analog signalsto digital signals. The touch signal detected in this embodiment isconverted into the digital signal and then is transferred to a signalprocessor 35 to be described later with reference to FIG. 15.

As shown in FIG. 9, if a bodily finger 25 approaches the sensor pattern10 within a certain distance from the sensor pattern 10, a touchcapacitance “Ct” is formed between the finger 25 and the sensor pattern10. Ct is a value that is set by the relational formula of FIG. 7, andmay be freely made by adjusting an interval between a touch unit such asa bodily finger 25 and the sensor pattern 10, and an opposite area ofthe sensor pattern 10. For example, if the sensor pattern 10 is selectedas a large area, the touch capacitance “Ct” is also made to have a largevalue based on the relationship formula of FIG. 7. In contrast, if thesensor pattern 10 is selected as a small area (for example, 1 mm² orless), the touch capacitance “Ct” is also designed to have a smallvalue. As an embodiment, the touch capacitance “Ct” may be designed tohave a value of tens of fF (femto F) to tens of uF (micro F).

The symbol “Cp” of FIG. 9 is a parasitic capacitor. The “Cp” is the sumof values of capacitors other than capacitors defined as “Ct” or “Caux”and may be modeled as a capacitor whose one end is connected to thetouch detection sensor 14 and the other end of which is connected to anyground. Thus, a plurality of differently grounded parasitic capacitors(Cp) can be formed, but only one ground is assumed in the presentspecification, and only one parasitic capacitor connected to the onlyone ground has been shown. The parasitic capacitor (Cp) may be aparasitic capacitor that occurs between the sensor signal line 22 andthe display device, or a parasitic capacitor that occurs between thesensor signal lines 22 when a plurality of the sensor patterns 10 areprovided in a dot matrix form, and thus the sensor signal lines 22 arewired in parallel to each other.

Referring to FIG. 9, a pre-charge voltage (Vpre) is applied to the inputterminal of the charging unit 12, and the pre-charge voltage (Vpre) isoutput through the output terminal when the switching device is turnedon by a control voltage (Vg) which is applied to a control terminal.Thus, all capacitors connected to the output terminal of the chargingunit 12 are charged as the pre-charge voltage (Vpre).

According to an embodiment, assuming that the switching device is turnedon when Vpre is 3 V and Vg varies from 0 V (Zero Volt) to 10 V, theauxiliary capacitor (Caux), the touch capacitance (Ct), and theparasitic capacitor (Cp) are charged as 3 V. After being charged, thecontrol voltage (Vg) of the switching device is fallen from 10 V to 0 Vto thus turn off the switching device, and a point “P” of the touchdetection sensor is in a high-impedance state, to thus isolate electriccharges at the point “P” and then an alternating driving voltage isapplied to the auxiliary capacitor (Caux). In this case, the magnitudeof the voltage detected at the point “P” depends on the magnitude of thecapacitors connected to the point “P” and the magnitude of the drivingvoltage.

At this point, assuming Caux and Cp are fixed values, and the magnitudeof the driving voltage is constant, the magnitude of the voltagedetected at the point “P” depends on the touch capacitance (Ct). Thus,since the voltage detected in the touch detection sensor 14 variesdepending on the magnitude of the touch capacitance (Ct), it is possibleto detect the presence of the touch input by detecting the voltagedifference and to compute the opposite area between the sensor pattern10 and the touch input instrument such as the finger 25.

In this embodiment, it was assumed as follows. The voltage drop due tothe on-resistance (Rdson) of the switching device was ignored. Inaddition, the magnitude of the auxiliary capacitor (Caux) is determinedat the manufacturing process of the auxiliary capacitor (Caux), and thusonce the magnitude of the auxiliary capacitor (Caux) is determined, themagnitude of the auxiliary capacitor (Caux) does not change. Inaddition, the magnitude of the parasitic capacitance (Cp) does not alsochange.

Meanwhile, in the case that the sensor pattern 10 of FIG. 9 is mountedas a touch screen panel on the upper surface of the display panel or isembedded in the display device, a common electrode capacitor (Cvcom) isformed between the sensor pattern 10 and the common electrode of thedisplay device. Otherwise, a common electrode capacitor (Cvcom) may beartificially formed by forming a common electrode 220 on the othersurface of the substrate in which the sensor patterns 10 are formed.

FIG. 10 is a cross-sectional view showing a configuration of sensorpatterns according to an embodiment of the present invention, and FIG.11 is a cross-sectional view showing a configuration of sensor patternsaccording to another embodiment of the present invention. FIG. 10illustrates that the sensor patterns 10 are mounted on a substrate thatis formed separately from the display device, and FIG. 11 illustratesthat the sensor patterns 10 are embedded in the display device, or acommon electrode 220 is formed on the other surface of the substrate inwhich the sensor patterns 10 are formed. Referring to FIGS. 10 and 11,the formation of the common electrode capacitor (Cvcom) will bedescribed as follows.

As shown in FIG. 10, the display device 200 has the common electrode220. An AMOLED display device does not have a common voltage thatfunctions to display the quality of image, but a virtual electricpotential layer that can form the common electrode capacitor (Cvcom) ofFIG. 9 is formed between the TFT substrate 205 and the sensor pattern10, which is also named a common electrode.

The display device 200 may be formed in various forms as describedabove. The common electrode 220 may be an electrode of a common voltage(Vcom) in a liquid crystal display (LCD), or may be one of other typesof electrodes. Among a variety of display devices, the LCD has beenillustrated in the embodiment of FIG. 10.

In the display device 200 shown in FIG. 10, liquid crystal is sealed andfilled between a lower-side thin film transistor (TFT) substrate 205 andan upper-side color filter 215, to thus have a structure of forming aliquid crystal layer 210. To seal the liquid crystal, the TFT substrate205 and the color filter 215 are joined by sealants 230 at their outerportions. Although they are not shown, polarizing plates are attached onthe top and bottom of the LCD panel, and besides optical sheets such asa back light unit (BLU) and a brightness enhancement film (BEF) areprovided.

As shown, a substrate 50 of a touch screen panel is provided on top ofthe display device 200. As shown in FIG. 10, the substrate 50 isattached to the upper portion of the display device 200 at the outerportion thereof, through the medium of an adhesive member 57 such as adouble adhesive tape (DAT), and an air gap 58 is formed between thesubstrate 50 and the display device 200.

A common voltage level alternating at a predetermined frequency andwhose magnitude varies, or a common voltage direct-current (DC) level ofa constant magnitude is applied to the common electrode 220 of thedisplay device 200 as shown in FIG. 10. For example, a line-inversiontype small-sized LCD has an alternating common voltage of the commonelectrode 220 as shown in FIG. 5, and the other dot-inversion type LCDssuch as a notebook computer, monitor, or TV have a common voltagedirect-current (DC) level of a constant magnitude voltage.

As shown, the common electrode capacitance (Cvcom) is formed between thesensor pattern 10 and the common electrode 220 of the display device200. If a certain pre-charge signal is applied to the sensor pattern 10,the common electrode capacitance (Cvcom) will have a predeterminedvoltage level by a charging voltage. In this case, one end of the commonelectrode capacitance (Cvcom) is grounded with the common electrode 220and so, when a voltage applied to the common electrode 220 is analternating voltage, the electric potential of the sensor pattern 10that is at the other end of the common electrode capacitance (Cvcom)will alternate by the alternating voltage applied to the commonelectrode 220. When the DC voltage is applied to the common electrode,the electric potential of the sensor pattern 10 does not alternate.

Meanwhile, a reference numeral 24 in the drawing denotes a protectivelayer 24 to protect the sensor pattern 10.

FIG. 11 shows an embodiment of the case where the sensor pattern 10 isbuilt in the display device. Referring to FIG. 11, the substrate 50 thatconfigures the touch screen panel may be a color filter 215 that is apart of the display device. As shown, the common electrode 220 is formedat the lower portion of the color filter 215, and the sensor patterns 10are patterned on the top surface of the color filter. In the FIG. 11embodiment, the protective layer 24 is replaced by a polarizer.

In this embodiment, the common electrode capacitance (Cvcom) is alsoformed between the common electrode 220 and the sensor pattern 10. If analternating voltage is applied to the common electrode, the electricpotential of the sensor pattern 10 is induced and alternates by thealternating voltage and if a DC voltage is applied to the commonelectrode, the electric potential of the sensor pattern 10 does notalternate by the common voltage of the common electrode.

In addition, in the embodiment of FIG. 11, the sensor patterns 10 arepatterned on the top surface of the substrate 50 and the commonelectrode 220 is artificially formed on the lower surface of thesubstrate 50 as an example. In this case, the protective layer 24 is alayer to protect the sensor patterns 10. For example, the protectivelayer 24 may be formed of a glass or plastic film. If a protection panelsuch as reinforced glass is attached on the upper surface of thesubstrate 50, the protective layer 24 can be removed.

In this case, the common electrode capacitance (Cvcom) is also formedbetween the sensor pattern 10 and the common electrode 220. A structureof artificially forming the common electrode 220 on the rear surface ofthe sensor pattern 10 as described above, can be selected for thepurpose of forming the touch screen panel so as to be separated from thedisplay device 200 and avoiding the noise coming from the display device200.

In the three embodiments described with reference to FIGS. 10 and 11, inthe case that the voltage of the sensor pattern 10 is synchronized withthe alternating common voltage and thus alternates, the pre-chargevoltage through the charging unit 12 should proceed to avoid the risingedge and falling edge of the alternating voltage, to thereby avoidinfluences due to the alternating common voltage, and detaileddescription of waveforms will be described later.

Referring to the circuit diagram of FIG. 9, the auxiliary capacitor(Caux), the touch capacitance (Ct), the common electrode capacitance(Cvcom), and the parasitic capacitance (Cp) acting on the sensor pattern10 are connected to the output terminal of the charging unit 12. Thus,when a pre-charge signal such as any voltage or current is applied tothe input terminal of the charging unit 12 at a state where the chargingunit 12 has been turned on, Caux, Ct. Cvcom, and Cp are charged.Thereafter, if the charging unit 12 is turned off, the charged signal isisolated unless the charged signals are separately discharged from thefour capacitors Caux, Ct, Cvcom, and Cp.

To stably isolate the charged signals, the input end of the touchdetection sensor 14 has a high-impedance (or Hi-z) state. Preferably,the input end of the touch detection sensor 14 has an impedance of atleast one Mohm(Mega Ohm). If a touch input is observed while dischargingthe signals charged in the four capacitors, the charged signals areisolated in the other ways, or the signals are quickly observed at thetime of discharge initiation, there is no need to inevitably have ahigh-impedance (or Hi-z) state at the input end of the touch detectionsensor 14.

The touch detection sensor 14 detects whether or not a signal level ofthe sensor pattern 10 is shifted. Preferably, the touch detection sensor14 detects whether or not a voltage difference occurs as a difference inthe magnitude of a voltage of the sensor pattern 10 at the time ofoccurrence of a touch input (that is, when Ct is formed), in contrast tothe magnitude of a voltage of the sensor pattern 10 at the time ofnon-occurrence of a touch input (that is, when Ct is not formed), tothus acquire a touch signal. The touch detection sensor 14 may have awide variety of devices or circuit configuration. In the embodiments tobe described later, examples in which a switching device and adifferential amplifier are used as the touch detection sensor 14 will bedescribed, but the configuration of the touch detection sensor 14 is notlimited thereto.

Unlike the connection method of the auxiliary capacitor (Caux) of FIG.9, one side of the auxiliary capacitor (Caux) is connected to thecontrol terminal of the charging unit 12 in the case of the embodimentof the touch detection sensor of FIG. 12. In this embodiment, themagnitude of the signal applied to the auxiliary capacitor (Caux) or thepoint in time at which the signal is applied, is dependent on theoperation of the control terminal of the charging unit 12, as drawbacks,but the auxiliary capacitor (Caux) can be embedded in the charging unit12, and a portion of forming the driving voltage applied to theauxiliary capacitor (Caux) does not exist separately, as advantages.

The voltage difference of the sensor pattern 10 due to the auxiliarycapacitor (Caux) and the driving voltage applied to the auxiliarycapacitor (Caux) at the time of non-occurrence of a touch input isdetermined by following Equation 1.

$\begin{matrix}{{\Delta \; {Vsensor}} = {{\pm \left( {{Vh} - {V\; l}} \right)}\frac{Caux}{{Caux} + {Cvcom} + {Cp}}}} & 1\end{matrix}$

Since Ct is added in parallel in the touch detection sensor 14 at thetime of occurrence of a touch input, the voltage difference of thesensor pattern 10 is determined by following Equation 2.

$\begin{matrix}{{{\Delta \; {Vsensor}} = {{\pm \left( {{Vh} - {V\; l}} \right)}\frac{Caux}{{Caux} + {Cvcom} + {Cp} + {Ct}}}},} & 2\end{matrix}$

In Equations 1 and 2, ΔVsensor is a voltage difference in the sensorpattern 10 or the touch detection sensor 14, Vh is a high level voltageof the drive signal applied to the auxiliary capacitor (Caux), or aturn-on voltage applied to a control terminal of the charging unit 12,Vl is a low level voltage of the drive signal applied to the auxiliarycapacitor (Caux) or a turn-off voltage applied to the control terminalof the charging unit 12. Cvcom is a common electrode capacitance, Cp isa parasitic capacitance, and Ct is a touch capacitance.

The touch detection sensor 14 detects a voltage difference that is adifference in voltages between Equations 1 and 2 in the sensor pattern10 by using Equations 1 and 2, which will be described below in detail.

In Equations 1 and 2, Vh and Vl are values that may be easily set up.Cvcom may be obtained from following Equation 3.

$\begin{matrix}{{Cvcom} = {{ɛ1}\frac{S\; 1}{D\; 1}}} & 3\end{matrix}$

In Equation 3, ∈1 may be obtained from the composite dielectric constant(or permittivity) of media existing between the sensor pattern 10 andthe common electrode 220. For example, since the specific dielectricconstant is 3 to 5, in the case of glass, the dielectric constant of thesubstrate 50 may be obtained by multiplying the specific dielectricconstant of glass by the dielectric constant of vacuum. In the case ofFIG. 10, since glass, an air space, a polarization plate, and anadhesive for attaching the polarization plate onto glass exist betweenthe sensor pattern 10 and the common electrode 220. S1 is an oppositearea between the sensor pattern 10 and the common electrode 20, whichwill be easily calculated. In the case that the common electrode 220 isformed over the entire lower surface of the color filter 215 as shown inFIG. 10, the opposite area S1 is determined by an area of the sensorpattern 10. In addition, D1 is a distance between the sensor pattern 10and the common electrode 220, and thus corresponds to thickness of themedium 50.

As seen, Cvcom is a value that may be easily obtained and set.

The touch capacitance Ct may be obtained from following Equation 4.

$\begin{matrix}{{Ct} = {{ɛ2}\frac{S\; 2}{D\; 2}}} & 4\end{matrix}$

In Equation 4, the permittivity ∈2 may be obtained from a medium betweenthe sensor pattern 10 and the finger 25. If reinforced glass is attachedon the top surface of the substrate 50, in FIG. 10, the permittivity ∈2can be obtained by multiplying the specific dielectric constant of thereinforced glass by the dielectric constant of vacuum. S2 corresponds toan opposite area between the sensor pattern 10 and the finger 25. If thefinger 25 covers the entire surface of a certain sensor pattern 10, S2corresponds to the area of the certain sensor pattern 10. If the finger25 covers part of a certain sensor pattern 10, S2 will be reduced fromthe area of the sensor pattern 10, by an area of the certain sensorpattern that is not covered with the finger 25. In addition, D2 is adistance between the sensor pattern 10 and the finger 25, and thuscorresponds to thickness of reinforced glass or the planarization layer24 that is put on the upper surface of the substrate 50.

As described above, Ct is a value that can be also easily obtained, andthat can be also set up by using the material and thickness of theprotection panel 24 or the reinforced glass that is put on the uppersurface of the substrate 50. In particular, according to the Equation 4,since Ct is proportional to the opposite area between the finger 25 andthe sensor pattern 10, a touch share of the finger 25 with respect tothe sensor pattern 10 can be calculated from the Ct.

The touch detection sensor 14 detects whether or not there is a voltagedifference that is a difference in the magnitude of a voltage due to theEquation 2 in comparison with the magnitude of a voltage due to theEquation 1. The touch detection sensor 14 may include an amplifier toamplify a signal from the sensor pattern 10, an analog to digitalconverter (ADC), a voltage to frequency converter (VFC), a flip-flop, alatch, a buffer, a transistor (TR), a thin film transistor (TFT), acomparator, a digital to analog converter (DAC), an integrator, adifferentiator, etc., or a combination of these components.

FIG. 9 illustrates the touch detection sensor 14 includes an analog todigital converter (ADC) 14 a. Referring to FIG. 9, the sensor pattern 10is connected to the input terminal of the ADC 14 a. Thus, the voltagedifference in the sensor pattern 10 is detected through the inputterminal of the ADC 14 a. As shown, if a junction between the sensorpattern 10 and the input terminal of the ADC 14 a is P, the electricpotential Vp of the junction P is affected by the touch capacitance Ctas expressed in the Equations 1 and 2.

Meanwhile, as described above, the ADC 14 a shown in FIG. 9 is an analogto digital converter (ADC) having a buffer input with a high impedancestate, or is configured by a combination of such a buffer. In the casethat throughout this specification, the ADC or the differentialamplifier is used as part of the touch detection sensor 14, it hasdeemed to have been combined with the buffer of the high-impedancestate.

As shown, a driving voltage that has a certain pitch and alternates isapplied to one end of the auxiliary capacitor (Caux). Although notshown, in one embodiment, the driving voltage is a CMOS output of aninverter or an “AND Gate”, or is the output of a device that may outputan alternating voltage like the output of an OP-AMP. Thus, the electricpotential of Vp is in synchronization with the driving voltage appliedto the auxiliary capacitor (Caux), and alternates, at a state where theauxiliary capacitor (Caux) is pre-charged (or charged) by the chargingvoltage expressed as Vpre. Thereafter, while a supply of the chargingvoltage and alternation of the driving voltage continue successively, Vphas the magnitude of the voltage of the Equation 1 at the time ofnon-occurrence of a touch input. If a touch input occurs, Ct is added inthe denominator of the Equation 1, to thus become Equation 2. Therefore,the voltage of Vp is reduced, and thus the voltage difference occurs,which is obtained by subtracting the Equation 2 from the Equation 1.

FIG. 13 is waveform diagram illustrating a process of detecting a touchsignal in the embodiment of FIG. 9. Referring to FIG. 13, a method ofdetecting a touch signal by using a voltage difference will be describedbelow.

In the FIG. 13 embodiment, the waveforms are divided into three areas.The first area of FIG. 13 is an interval named a “No Touch” area whereno touch inputs occur and there is no touch capacitance (Ct). The secondarea of FIG. 13 is an interval named a “Full Touch” area where thefinger 25 completely covers the sensor pattern 10 and the touchcapacitance (Ct) of the Equation 4 is maximized. On the other hand, thelast area positioned in the lower-right corner of FIG. 13 is an intervalnamed a “½ Touch” area where the finger 25 covers only 50% of the sensorpattern 10 and the touch capacitance (Ct) has a size of 50% compared tothe Ct of the “Full Touch” area.

As mentioned earlier, in one embodiment of the present invention, acommon voltage may be an alternating voltage alternating with a constantfrequency, or a DC voltage that does not alternate or an AC voltage thatalternates aperiodically. In this embodiment, the common voltagealternates in the “No Touch” area and the “Full Touch” area, and has aDC voltage of 0 V (zero Volt) in the “½ Touch” area. It can be seen thatthe present invention can be carried out regardless of the form of thecommon voltage. However, the rising edge and the falling edge may besensed even for the common voltage (Vcom) that is non-periodic, tothereby configure embodiments in the same method as that of the commonvoltage (Vcom) that is periodic of the present embodiment.

In order to proceed with the present embodiment, an unshown commonvoltage detector should detect the common voltage. If the waveform ofthe rising edge and falling edge of the common voltage is applied at aninterval at which the voltage difference is detected in the case thatthe common voltage alternates with a certain size, the waveforms thatare detected in the touch detection sensor 14 may be distorted due tothe waveform of the common voltage. Accordingly, the present inventiondetects voltage differences of the pre-charge and touch signal whileavoiding the points in time at which the rising edge and falling edge ofthe common voltage occur. However, in another embodiment, as in theexemplary embodiment of the present invention, both a voltage differencethat occurs when the driving voltage is applied to one side of theauxiliary capacitor (Caux), and a voltage difference that occurs at therising edge and falling edge of the common voltage may be detectedtogether, to thus detect the touch input.

If a common voltage is a DC level that does no alternate, it is possibleto detect a voltage difference that does not depend on the waveform ofthe common voltage. A drive IC 30 that will be described later mayinclude a mode setter unit of setting a mode of detecting the commonvoltage in the case that the common voltage alternates, to thus sensethe rising edge and falling edge of the common voltage and refer to thesensed rising edge and falling edge thereof, and a mode where the commonvoltage is not referred to when the common voltage does not alternate.Because of this action, when the common voltage does not alternate, itis possible to detect the voltage difference more easily.

As described above, when the common voltage is first detected and thenthe common voltage alternates, the voltage difference can be detectedwhile avoiding the points in time at which the common voltagealternates. Thus, according to benefits of this approach, the voltagedifference due to the touch input can be detected in any display devicesin which the common voltage alternates or does not alternate.

*Embodiment in the “No Touch” Area

The waveform of the common voltage is first detected to then detect theedges of the waveform of the common voltage, and then the ON/OFF controlterminal of the charging unit 12 is turned on after a predetermined time(indicated as ‘t1’ in this embodiment) to thereby charge capacitors. Thecapacitors that are charged in the non-touch area are Caux, Cvom, andCp. The intervals at which the capacitors are charged are intervals{circle around (2)} and {circle around (7)} in FIG. 13.

The intervals {circle around (1)} and {circle around (6)} in FIG. 13 areintervals at which voltage of Vp is dependent on the waveform of thecommon voltage by the alternating common voltage, in which the voltageof Vp is applied as 0 V at the interval {circle around (1)}, but themagnitude of the voltage of Vp is determined by a specific formula atthe interval {circle around (6)} which will be described later.

If the charging unit 12 is turned off after having charged thecapacitors, the input end of the touch detection sensor 14 is in a Hi-zstate, that is, in a high impedance state, and thus the charges storedin the capacitors remain isolated. As a result, the electric potentialof the sensor pattern 10 is also maintained. In this example, the ONvoltage of the charging unit 12 is 5 V and the OFF voltage thereof is 0V.

The pre-charge signal (Vpre) is applied to 5 V as an example, and may beturned on and off in synchronization with the gate signal (Vg), or mayremain always the ON state. The common voltage of the common electrode220 of the display device 200 was assumed to be given 5 V at the highlevel, and −1 V at the low level.

Meanwhile, assuming the driving voltage (Vdrv) applied to the auxiliarycapacitor (Caux) is 9 V at the high level, and 0 V at the low level, thecharging operation is first performed and then the detection operationis performed at the rising time and falling time of the driving voltage,which are performed at the intervals {circle around (4)} and {circlearound (8)}, as shown in FIG. 13.

In the example in FIG. 13, when the pre-charge is performed at theintervals {circle around (2)} and {circle around (7)}, the electricpotential of Vp becomes 5 V. In the waveform of FIG. 13, the effects oftransients and noise at the charging and discharging time were ignored.

Thereafter, even if Vg is turned off, the charges stored on thecapacitors remain isolated and the electric potential of Vp is kept at 5V. The detection operation is performed at the intervals (the interval{circle around (4)} and the interval {circle around (8)}), and thus atouch has not still occurred, the voltage by the Equation 1 is formed.Assuming that Caux, Cvcom and Cp are all one depending on the relativesize, the driving voltage rises up at the interval {circle around (3)},and the voltage of Vp rises up in synchronization with the risingdriving voltage. The value of ΔVsensor at the interval {circle around(4)} is “{9−(0)}*⅓” according to the Equation 1, so is 3 V. Thus, theelectric potential (Vp) at the point P ranges from 5 V to 8 V and variesin synchronization with the size of the driving voltage. On the otherhand, a waiting time t2 that is taken until the driving voltage variesafter the pre-charge has occurred at the interval {circle around (2)} isseveral μs to several tens μs, as an example, but the waiting time t2 ispreferably several μs.

The voltage detected at the interval {circle around (4)} is stored inthe memory and is used as comparison data to be compared with a voltagedetected at the time of occurrence of a touch input. Thus, the detectionvoltage at the interval {circle around (4)} in the “No Touch” area ismeasured and stored in the memory, at a state where no touch inputoccurs such as a “factory mode” (a part of a manufacturing process) or a“Calibration mode,” and is used as reference data to detect a voltagedifference in comparison with a “touch mode” when a touch input occurs.

If the detection operation is performed at the falling edge of thedriving voltage (Vdrv) on the contrary with the above case, at theinterval {circle around (5)} after the interval {circle around (4)}, thevalue of ΔVsensor is “−{9−(0)}*⅓,” and so is −3 V. Thus, the electricpotential (Vp) at the point P will be changed from 8 V to 5 V. The datathat has been measured through the operation process will be able toincrease the reliability of the data.

Referring to FIG. 13, the common voltage alternates at the interval{circle around (6)} in which voltage of Vp is determined by thefollowing equation.

$\begin{matrix}{{\Delta \; {Vsensor}} = {{\pm \left( {{VcomH} - {VcomL}} \right)}\frac{Cvcom}{{Caux} + {Cvcom} + {Cp}}}} & 5\end{matrix}$

In the Equation 5, ΔVsensor represents a voltage difference in thesensor pattern 10 or the touch detection sensor 14. VcomH is a highlevel voltage of the common voltage applied to the common electrodecapacitor (Cvcom), VcomL is a low level voltage of the common voltageapplied to the common electrode capacitor (Cvcom), Cvcom is a commonelectrode capacitance, and Cp is a parasitic capacitance.

According to the Equation 5, at the interval {circle around (6)} wherethe common voltage falls down, the size of ΔVsensor is “−{5−(−1)}*⅓,”and so is −2 V, and the electric potential of Vp is 5 V before variationof the common voltage occurs. Thus, the electric potential of Vp is 3 Vat the interval {circle around (6)}.

Since the voltage difference due to the touch can be detected even atthe interval from the interval {circle around (5)} to the interval{circle around (6)}, it is possible to detect whether or not a touchinput occurs and to detect a touch area share in sensor pattern 10. Thisis because the detection voltage detected in the touch detection sensor14 is calculated by the following Equation 6, if a touch input occursfrom the interval {circle around (5)} to the interval {circle around(6)} and thus the touch capacitance Ct is produced.

In the Equation 6, Ct denotes the touch capacitance.

When comparing the Equations 5 and 6, it is the difference between theEquations 5 and 6 that Ct has been added to the denominator of theEquation 6. It can be seen that the magnitude of the voltage detected inthe touch detection sensor 14 depending on the size of Ct, that is, avoltage difference that is a difference between the values of theEquations 5 and 6 represents a degree of the touch. However, since thismethod requires an alternating common voltage, it is impossible todetect the touch in the case that the common voltage does not alternatelike the “½ Touch” area. However, the drawback can be solved by applyingthe alternating common voltage to the common electrode.

Since the interval {circle around (7)} in FIG. 13 is a charginginterval, the electric potential of Vp is charged as 5 V, and thedriving voltage at the interval {circle around (8)} falls down from highto low. Thus, ΔVsensor at the interval {circle around (8)} is“−{9−(0)}*⅓,” and so is −3 V, and the charging voltage that is 5 V atthe point P is changed into 2 V.

*Embodiment in the Full Touch Area

Referring to FIG. 13, the area S in the Equation 4 is fully occupied bythe finger 25 at the interval {circle around (9)} in which Ct representsthe maximum value. If the relative size of Ct is three (3) when comparedto Cvcom or Caux whose relative size is one (1), ΔVsensor at theinterval {circle around (9)} is determined by the Equation 6, andΔVsensor is “{5−(−1)}*⅙,” and so is 1 V. Thus, the detection voltage is2 V at the interval {circle around (8)}, the voltage is 3 V at theinterval {circle around (9)}.

As mentioned earlier, since the voltage difference of 1 V (=2 V−1V) inΔVsensor occurs when Ct exists and does not exist depending on whetheror not the touch occurs in the Equation 6, the touch detection sensor 14detects the voltage difference and thus detects whether or not a touchoccurs and compute the opposite area between the sensor pattern 10 andthe touch instrument such as the finger 25.

At the interval {circle around (10)}, ΔVsensor is determined by theEquation 2, and the size of ΔVsensor is “{9−(0)}*⅙” by the risingdriving voltage and so is 1.5 V. Since the magnitude of the detectionvoltage is 5 V at the charging interval before the interval {circlearound (10)}, the detection voltage is 6.5 V at the interval {circlearound (10)}.

In the “No Touch” area, the magnitude of the detection voltage is 8 V atthe interval {circle around (4)} at which the magnitude of the detectionvoltage is defined by the Equation 1, and in the “Full Touch” area, themagnitude of the detection voltage is 6.5 V at the interval {circlearound (10)} at which the magnitude of the detection voltage is definedby the Equation 2. Accordingly, the voltage that is obtained bysubtracting the Equation 2 from the Equation 1, that is, the voltagedifference is 1.5 V. The touch detection sensor 14 detects the size ofthe voltage difference and determines whether or not a touch occurs.

At the interval {circle around (11)}, the detection voltage is definedby the Equation 2. The size of ΔVsensor is “{9−(0)}*⅙” that is 1.5 V atthe interval {circle around (11)}. Since the charging voltage is 5 Vjust before the interval {circle around (11)}, the detection voltage isdetected as 3.5 V. The detection voltage is 2 V due to the voltagedifference defined by the Equation 1 in the “No Touch” area, but thedetection voltage is 3.5 V at the interval {circle around (11)}. Thus,the difference in the voltages, that is, the voltage difference is 1.5V, and thus is the same as the voltage difference that was describedabove. Thus, it can be seen that the size of the voltage difference hasan identical value regardless of whether the driving voltage (Vdrv) isat the rising edge or falling edge. Accordingly, the voltage differencescan be all detected at the rising edge or falling edge of the drivingvoltage (Vdrv).

*Embodiment of ½ Touch Area

Meanwhile, if the finger 25 partially covers the sensor pattern 10, theopposite area S2 between the finger 25 and the sensor pattern 10 becomessmaller in the Equation 4, and thus Ct also decreases. Thus, in the FIG.13 waveform diagram, the size of the voltage difference will becomesmaller too. In other words, if the amount of the voltage difference isdetected, the touch share of the finger 25 for the sensor pattern 10 canbe computed. Such a function makes it possible to increase a touchresolution although the size and resolution of the sensor pattern 10 arelimited. In addition, such a function makes it possible to detect thesubtle changes in the touch coordinates and to draw a high-resolutionpicture by using the finger or other touch input instruments.

If the finger 25 covers 50% of the sensor pattern 10, Ct has a relativevalue of 1.5 that is half of the “Full touch” time by the Equation 4. Inthe “½ Touch” area, the common voltage does not alternate. Thus, thereis no need to apply the driving voltage (Vdrv) to avoid the moment thecommon voltage alternates. Therefore, the detection time does not dependon Vcom and is randomly adjusted.

Since Ct is 1.5 at the interval {circle around (12)}, ΔVsensor is“{9−(0)}* 1/4.5,” and so is 2 V. Since the charging voltage is 5 V justbefore the interval {circle around (12)}, the detection voltage isdetected as 7 V at the interval {circle around (12)}. The detectionvoltage at the interval {circle around (13)} at which the drivingvoltage (Vdrv) is at the falling edge, becomes 3 V in which 2 V issubtracted from 5 V that is the charging voltage. Thus, the touchdetection sensor 14 measures a voltage difference that is a differencebetween values of the detection voltage at the interval {circle around(4)} or {circle around (8)} and the detection voltage at the interval{circle around (12)} or {circle around (13)}, in the “No Touch” area, tothus make it possible to calculate the opposite area between the sensorpattern 10 and the finger 25.

FIG. 9 illustrates the case that the auxiliary capacitor (Caux) does notdepend on the behavior of the ON/OFF control terminal of the chargingunit 12, but FIG. 12 shows an embodiment of the case that the drivingvoltage (Vdrv) applied to the auxiliary capacitor (Caux) is dependent onthe ON/OFF control signal of the charging unit 12. Such an embodimenthas an advantage that the circuit is simple since there is no need toseparately produce the driving voltage (Vdrv) applied to the auxiliarycapacitor (Caux), but has some drawbacks that the driving voltage (Vdrv)depends on the control voltage of the charging unit 12, it is notpossible to detect the voltage difference since the output terminal ofthe charging device 12 is not at the Hi-z state, that is, at the highimpedance state, and the detection speed slows down since it is possibleto detect the voltage difference at the time when the control voltagefalls down. However, these drawbacks can be overcome by the fastcharging operation and the fast detecting operation of the charging unit12.

On the other hand, FIG. 12 shows the case that an amplifier 18 is usedas the touch detection sensor 14. The amplifier 18 whose input end is atthe Hi-z state, or that is combined with a buffer whose input end is atthe Hi-z state can also reliably isolate a signal at the point P.

In the embodiment of FIG. 12, the fact that the electric potential atthe point P varies by Ct to thus cause the voltage difference is thesame as the embodiment of FIG. 9. However, the amplifier 18 is used as adetection unit that detects the voltage difference. The amplifier 18amplifies the signal from the sensor pattern 10. Accordingly, since thevoltage difference due to occurrence of a touch input is amplified andoutput, a touch signal can be reliably obtained even if the value of thevoltage difference is small.

In addition to the amplifier 18, a differential amplifier 18 a can beused. Referring to FIG. 12, the electric potential at the point P isinput to the input terminal of the differential amplifier 18 a inaddition to the amplifier 18, and a reference voltage (Vdif) for forminga differential voltage is input to another input terminal of thedifferential amplifier 18 a. If the reference voltage (Vdif) is input tothe non-invert terminal of the differential amplifier 18 a, a value thatis obtained by subtracting the reference voltage (Vdif) from theelectric potential at the point P and then by multiplying thesubtraction result by an amplification factor of the differentialamplifier 18 a will be output as an output of the differential amplifier18 a. According to the advantage of this configuration, the level of thenoise applied to the point P is made to be small, to thus calculate asignal more stably and increase the accuracy of the touch operation. Inthe embodiment of FIG. 12, the amplifier 18 and the differentialamplifier 18 a are not used simultaneously, but only one of two isconnected to the point P.

Meanwhile, in FIG. 13, the pre-charge voltage (Vpre) is illustrated as a5V single voltage, but the magnitude of pre-charge voltage (Vpre) mayvary at the rising edge and falling edge of the driving voltage, and aplurality of pre-charge voltages may be used, as necessary. For example,the magnitude of the detection voltage is 8 V, at the interval {circlearound (4)} of FIG. 13, and thus may be beyond the scope of theresisting pressure in the case that a control IC whose resistingpressure is 5 V is used. In this case, the charging voltage (Vpre) canbe applied with 1 V, and accordingly the detection voltage at theinterval {circle around (4)} becomes 4 V to thus make it possible to usethe control IC in the range of meeting the resisting pressure of thecontrol IC.

On the other hand, Cp may vary for each sensor pattern 10. For example,it is extremely difficult to uniformly design the location of the sensorpattern 10, the wiring length, and other external factors for eachsensor pattern 10. In addition, Cvcom may also vary for each sensorpattern 10. If the voltage difference is large in size, such a deviationmay be ignored, but the smaller size the voltage difference may have,the deviation for each sensor pattern 10 is not negligible.

In order to solve the above problems, as shown in FIG. 14, the drive IC30 further includes a memory unit 28 that stores the signal processingresults of the touch detection sensor 14 or a signal processor 35 to bedescribed later, when no touch occurs in the respective sensor patterns10. The signal which is stored in the memory unit 28 is a value based onthe unique Cp and the unique Cvcom of each sensor pattern 10 and mayvary for each sensor pattern 10.

For example, the sensor patterns 10 can be scanned at once at the statewhere no touch occurs after the power is applied, or the output of thetouch detection sensor 14 or the processing results of the signalprocessor 35 can be obtained at a “factory mode” that is the state whereno touch occur before being shipped from a manufacturing factory. Thefactory default values are stored in the memory unit 28.

A value that is obtained when a touch occurs may be also stored in thememory unit 28. In addition, an extra memory unit that stores the valueobtained when there is a touch may be further provided. In addition, thedrive IC 30 compares values of an identical cell, and judges that atouch occurs when a voltage difference beyond a pre-set reference valueoccurs, to thus compute a touch share of the sensor pattern 10 throughthe operational computation.

In order to attenuate the influence of Cp, it is also possible to set avalue of Caux or Ct to be relatively higher than that of Cp, in theEquations 1 and 2. Caux is built in the drive IC or mounted on theoutside of the drive IC. When Caux is built in the drive IC, the size ofCaux is determined at a manufacturing process of ICs. Even when Caux ismounted on the outside of the drive IC, a component whose size can begrasped is mounted. Therefore, since a relatively small Cp may beimplemented, the influences of Cp that is determined by unknown factorsmay be minimized.

Referring to FIG. 14, when the sensor patterns 10 are arranged in theform of a dot-matrix pattern, and have a resolution of m*n, the memoryunit 28 consists of a table with m rows and n columns. For example, theoutput of the differential amplifier 18 a that has occurred at the timeof non-occurrence of a touch input and that has been assigned at theuppermost-leftmost corner of the sensor pattern 10 may be stored in anaddress of M1−1. In addition, the signal stored in the memory unit 28 isreferenced when it is detected whether or not a touch input occurs atthe uppermost-leftmost corner of the sensor pattern 10.

The value stored in each address of the memory unit 28 may beperiodically calibrated. The periodic calibration may be carried outwhen power is applied to the device, as described above, or in a dormantstate. As described above, if the output of differential amplifier 18 ais stored in the memory unit 28, at the time of non-occurrence of atouch input for each sensor pattern 10 (or respectively separately atthe time of non-occurrence and occurrence of a touch input),periodically calibrated, and referenced at the time of detecting a touchsignal, the touch signal may be stably acquired even in the case that aunique Cp is assigned for each sensor pattern 10.

FIGS. 15 to 22 show embodiments of a touch screen panel according to thepresent invention, respectively. FIGS. 15 and 16 show embodimentsemploying the above-described touch detecting device of FIG. 9 or 12, inwhich the sensor pattern 10 is arranged in the form of a dot-matrixpattern.

A configuration of the drive IC 30 is shown at the lower portion of FIG.15. The drive IC 70 includes a driver 31, a touch detection sensor 14, atiming controller 33, a signal processor 35, and a memory unit 28. Inaddition, the drive IC 70 further includes one of a common voltagedetector 43, a common voltage information receiver 45, and analternating voltage generator 37. In addition, as shown in FIG. 14, thedrive IC 70 is configured to include all of the common voltage detector43, the common voltage information receiver 45, and the alternatingvoltage generator 37, and select one of the common voltage detector 43,the common voltage information receiver 45, and the alternating voltagegenerator 37 by a selector 47.

A drive signal obtained from the drive IC 30 is delivered to a centralprocessing unit (CPU) 40. The CPU 40 may be a CPU of a display device, amain CPU of a computer device, or a CPU of a touch screen panel itself.For example, an 8-bit or 16-bit microprocessor may be built in orembedded to process a touch signal. Although it is not shown in thedrawing, a power supply may be further included in a systemconfiguration in order to generate a high or low voltage of signals fordetecting touch inputs.

The microprocessor embedded in the drive IC 30 may calculate touch inputcoordinates, to thus recognize gestures such as zoom, rotation, andmove, and deliver data such as reference coordinates (or central pointcoordinates) and gestures to the main CPU. In addition, themicroprocessor may calculate an area of a touch input to generate azooming signal, calculate a strength of the touch input, and recognizeonly a user's desired GUI object (for example, only a GUI object whosearea is frequently detected) as a valid input, in the case that aplurality of GUI objects are simultaneously touched, that is, themicroprocessor may process data in various forms, and output theprocessed result.

The timing controller 33 generates a time divisional signal of severaltens of milliseconds (ms), and the signal processor 35 transmits andreceives signals to and from each sensor pattern 10 through the driver31, respectively. The driver 31 provides the ON/OFF control signal (Vg)and the pre-charge signal (Vpre) of the charging unit 12. The ON/OFFcontrol signal (Vg) is time divided by the timing controller 33 andsequentially or non-sequentially for each sensor pattern 10. Asmentioned with reference to FIG. 13, the memory unit 28 is used to storean initial value at the time of non-occurrence of a touch input in eachsensor pattern 10, or to store a signal at the time of occurrence of atouch input, and has unique absolute addresses for the respective sensorpatterns 10.

As described above, the obtained coordinate values may be temporarilystored or the reference values at the time of non-occurrence of a touchinput may be stored by using only one memory unit 28. Otherwise, aplurality of memory units are provided to thus separately store thereference values at the time of non-occurrence of a touch input anddetected values at the time of occurrence of a touch input,respectively.

In the illustrated embodiment, the sensor pattern 10 has beenillustrated as an example of a resolution of 4*5, but actually has ahigher resolution. As a result, signals may be lost in the process ofdealing with many signals. For example, in the case that the signalprocessor 35 is in a “busy” state, the touch drive signal is notrecognized to thus miss a signal.

The memory unit 28 may prevent the loss of such a signal. For example,the signal processor 35 temporarily stores the detected touch signal inthe memory unit 28. In addition, the signal processor 35 scans theentire sensor pattern 10 and then judges whether or not a missing signalexists with reference to the memory unit 28. If touch coordinates arestored in the memory unit 28 although signals have been lost in thesignal processing, the signal processor 35 processes the correspondingtouch coordinates as normal inputs.

The common voltage information receiver 45 directly receives the commonvoltage information of the common electrode 220 from the display device200. In this case, it is very easy to obtain such information as thestarting point, the size, the rising edge and the falling edge of thecommon voltage. In addition, the signal processor 35 can easily processsignals in conjunction with the rising edge and falling edge of thecommon voltage. However, it is burdensome to have to transmit the commonvoltage information from the display device 200.

On the other hand, in the case that the common electrode 220 of thedisplay device 200 has a constant DC level, the alternating voltagegenerator 37 is able to be forced to apply the alternating voltage tothe common electrode 220. The alternating voltage generator 37 applies avoltage level alternating at a predetermined frequency to the commonelectrode 220 according to a time divisional signal of the timingcontroller 33. A frequency of the alternating voltage applied to thecommon electrode 220 can be adjusted by adjusting a resistor. Even inthis case, the signal processor 35 can easily process signals inconjunction with the rising edge and falling edge of the common voltage.However, it is burdensome to have to transmit the common voltageinformation to the display device 200.

However, the common voltage detector 43 automatically detects the commonvoltage information, and thus is not required to transmit and receiveinformation related to the common voltage from and to the display device200. In the case that the common voltage detected in the common voltagedetector 43 is an alternating signal, the signal processor 35 appliesthe driving voltage to the auxiliary capacitor (Caux) while avoiding therising edge or falling edge of the common voltage as shown in FIG. 12.The common voltage detector 43 may have a variety of circuitconfigurations.

In one embodiment such as that of FIG. 15, sensor signal lines 22 areplaced between the sensor patterns 10 in the active region where thesensor patterns 10 are mounted, and are connected with the drive IC 30.If a touch screen panel is mounted separately on the display device, oris embedded in the display device, the sensor signal lines 22 should beformed of ITO or IZO to form transparent signal lines, at least in thevisible region. According to the advantage of these wires, there is noneed to have a separate area for wiring the signal lines since theentire signal lines are not collected and transferred to the drive IC 30through a pathway. However, since the signal lines are placed betweenthe sensor patterns 10, it is burdensome to widen a gap between thesensor patterns 10.

Meanwhile, in the wiring method of the sensor signal lines 22 of FIG.15, since the length of the signal line connected to the sensor pattern10 located at the uppermost end differs from the length of the signalline connected to the sensor pattern 10 located at the lowermost end,the wiring resistances of the signal lines vary for each sensor pattern10. If a resistance value increases, a delay occurs when touch signalsare detected. Accordingly, if the width of the sensor signal line 22that is wired on the upper-more end is made to be wider than the widthof the sensor signal line 22 that is wired on the lower-more end, andthe width of the wire becomes narrower as it is closer to the drive IC30, it is possible to match the wiring resistances of all the signallines for all the sensor patterns 10. Thus, the signal processor 35 canperform detection of the touch signals more easily.

On the other hand, in the conventional method such as that of FIG. 2,the linear sensor patterns are formed of a transparent material, but thesignal lines that connect the linear sensor patterns with the touchdrive IC should be formed of opaque metal such as silver or copper tolower the resistance value. As a result, there is a problem that aplurality of masks should be used, thereby increasing the processingcost and degrading the yield. However, referring to Equations 1 and 2representing the touch detection using the voltage difference accordingto the present invention, resistance does not act as a variable.Therefore, resistance values of the sensor signal lines 22 can be setrelatively high. As a result, ITO or IZO having high resistance may beused to form the sensor signal lines 22. Thus, in the same configurationas that of FIG. 15, the sensor patterns 10 and the sensor signal lines22 can be configured with the same material as a transparent materialsuch as ITO or IZO, which means that the sensor patterns 10 and thesensor signal lines 22 are prepared with a single mask, to therebyprovide an effect of increasing the production cost and the yield.

FIG. 16 shows another embodiment of the touch screen panel. Referring toFIG. 16, the sensor patterns 10 and the sensor signal lines 22 areformed in the active region 90 of the substrate 50. The sensor signallines 22 may be wired with metal in the active region 90, but preferablymay be wired as the transparent signal lines 22 a in the active region90. The sensor signal lines 22 may be wired as the transparent signallines 22 a in the active region 90, and thus may be placed between thesensor patterns in the same manner as in the embodiment of FIG. 15, butthe sensor signal lines 22 may be wired as the transparent signal lines22 a in the active region 90 and may be wired as metal signal lines 22 bthat are connected with the transparent signal lines 22 a throughconnectors 59 in an invisible region 92, in the same manner as in theembodiment of FIG. 16. However, according to the drawback of this wiringmethod, the width of the invisible region 92 should be widened and thusit is difficult to slim the touch device.

The touch detection sensor 14 may be an analog to digital converter(ADC), a buffer or an amplifier that is mounted in the drive IC 30.However, as shown, if the differential amplifier 18 a is used as thetouch detection sensor 14, the touch signal from which noise is removedis amplified and processed, and thus it is easy to capture the touchsignal. In FIG. 16, the differential amplifier 18 a and the ADC 14 a arenot used together, but one of the two detects a touch input. If thedifferential amplifier 18 a detects a touch input, the ADC 14 a isconnected with the output end of the differential amplifier 18 a to thusconvert an analog signal output from the differential amplifier 18 ainto a digital signal.

Referring to FIG. 16, a comparator 19 is further connected to the outputend of the differential amplifier 18 a (or the output end of a bufferconnected to the point P although it is not shown in the drawing). Thecomparator 19 is used to automatically detect the rising edge and thefalling edge of the common voltage of the display device 200 when thecommon voltage alternates. Since the input end of the differentialamplifier 18 a is in a Hi-z state, that is, in a high impedance state,at a state where the charging unit 12 has been turned off, the sensorpattern 10 is electrically isolated to be a floating state. In thiscase, if the voltage level fluctuates in the common electrode 220 of thedisplay device 200, the electric potential of the sensor pattern 10 ischanged. In other words, the electric potential of the point Palternates in synchronization with the alternating common voltage. Thealternating voltage levels are formed high or low based on the chargingvoltage. If the voltage of the point P is directly connected to thecomparator 19, and thus is compared with 5 V that is a comparisonvoltage (such as the charging voltage in the waveform of FIG. 13),height of the common voltage can be read out.

If a touch input occurs, the width of the voltage difference at thepoint P will be smaller. As shown, after the voltage level at the pointP is amplified by the differential amplifier 18 a and then compared witha reference voltage (Vref) in the comparator 19, height of the commonvoltage can be read out. Thus, the common voltage detector 43 can beconstructed by using a simple circuit such as the comparator 19.

In the embodiment of FIG. 15 or 16, the sensor pattern 10 has a uniqueposition coordinate. The unique position coordinate of each sensorpattern can be identified regardless of by sequentially scanning eachsensor pattern or by scanning sensor patterns on a group basis, and thusit is possible to execute a multi-touch recognition of recognizing thatmultiple touches occur in multiple sensor patterns 10 according to thepresent invention.

Meanwhile, in the embodiments of FIG. 16, the charging unit 12 and thetouch detection sensor 14 are separately provided for each unit cell ofthe sensor patterns 10, but are only the exemplary embodiment. Forexample, a plurality of sensor patterns 10 may be grouped and connectedwith a charging unit 12 and a touch detection sensor 14, through amultiplexer (MUX).

FIG. 17 shows a way of increasing a touch resolution. Referring to FIG.17, a plurality of drive ICs 30 a and 30 b may be mounted on a substrate50. Preferably, when a plurality of drive ICs 30 a and 30 b are mounted,the drive ICs 30 a and 30 b are mounted on a glass substrate 50 in theform of a chip on glass (COG), as shown. The drive ICs 30 a and 30 bincludes a master driver IC 30 a that delivers touch signals externally,and a slave drive IC 30 b that is connected to the master drive IC 30 avia a communication channel 94 on the substrate 50.

A flexible printed circuit (FPC) 96 a for sending and receiving signalsexternally is connected to the master drive IC 30 a. Since the slavedrive IC 30 b communicates with the master drive IC 30 a through thecommunication channel 94, a separate FPC does not need to be connectedto the slave drive IC 30 b. However, in order to be distinguished frompower lines, a FPC 96 b for power delivery may be connected to the slavedrive IC 30 b as shown.

In order to prevent conflicts between signals detected by the masterdrive IC 30 a and signals detected by the slave drive IC 30 b, themaster drive IC 30 a gives priority to both the signals detected by themaster drive IC 30 a and the slave drive IC 30 b, or gives a scanningorder, or uses a separate memory space, to thereby process touchsignals. In addition, the master drive IC 30 a and the slave drive IC 30b may refer to mutual signals on the touch detection boundary surface.

For example, in the case of the full resolution of 10×20 (width×length)of FIG. 17, it is assumed that each of the ICs is responsible for touchdetection for an area of 10×10 (width×length). In this case, since themaster drive IC 30 a and the slave drive IC 30 b do not know touchinformation of areas beyond their own areas at the tenth and eleventhcontact points on the longitudinal cross-boundary surface, a detectingpower at the longitudinal tenth and eleventh areas will be reduced. Inother words, the touch detection linearity is lowered.

In order to solve these problems, a drive IC refers to informationrelative to another drive IC at an interface therebetween. For example,if the master drive IC 30 a detects a touch for the first to tenth areasin the vertical direction, the master drive IC 30 a refers to a signalof an area that is located at the longitudinal eleventh area and inwhich the slave drive IC 30 b detects a touch signal, and thus detectstouches of the longitudinal tenth sensor patterns 10. In addition, whenthe slave drive IC 30 b detects touches of the longitudinal eleventhsensor patterns 10, the slave drive IC 30 b refers to information of thelongitudinal tenth sensor patterns 10 that are governed by the masterdrive IC 30 a.

To do this, a memory unit is further provided, and thus the master driveIC 30 a and the slave drive IC 30 b receive a signal detected in theopposite IC via a communication line at the interface thereof and thenwrite the received signal on the memory unit, so as to be used foroperations in the signal processor 35.

FIG. 18 shows another embodiment of a touch screen panel. In theprevious embodiments of the touch screen panel, the sensor patterns 10are arranged in the form of a dot-matrix pattern, but in the embodimentof FIG. 18, the sensor patterns 10 are arranged in the form of a linearpattern. Referring to FIG. 18, x-axis linear sensor patterns 10 a andy-axis linear sensor patterns 10 b are crosswise arranged in the activeregion 90 of the substrate 50. Each of the linear sensor patterns 10 aand 10 b includes an opposite area portion 41 a for forming a touchcapacitance Ct with respect to a touch input instrument, and aconnection portion 41 b for connecting the opposite area portion 41 awith another opposite area portion 41 a. In addition, the x-axis linearsensor patterns 10 a and y-axis linear sensor patterns 10 b cross eachother at the connection portions 41 b, to thus form crossing portions42.

The crossing portions 42 are intended to mutually isolate the linearsensor patterns 10 a and 10 b of the mutually different axes. Forexample, the connection portions 41 b of the x-axis linear sensorpatterns 10 a are first formed, and then an insulating layer is formedon top of the connection portions 41 b of the x-axis linear sensorpatterns 10 a, and then the connection portions 41 b of the y-axis ofthe linear sensor patterns 10 b are formed in the form of a bridge so asto pass over the insulating layer.

The big advantage of the embodiment of FIG. 18 is that the number of thesignal lines 22 wired in the active region 90 or the invisible region 92of the substrate 50 is greatly reduced. If the sizes of the sensorpatterns 10 are designed to be small, the physical touch resolution maybe increased compared to the preceding embodiments even though thenumber of the sensor signal lines 22 that are placed between the sensorpatterns 10 in the invisible region 92 or the active region 90 of thesubstrate 50 is not designed to become large.

In the embodiment having a linear array of FIG. 18, the x-axis linearsensor patterns 10 a and the y-axis linear sensor patterns 10 b maydetect whether or not touches occur on one of the x-axis and y-axis andthen whether or not touches occur on the other of the x-axis and y-axis,or may detect whether or not touches occur on both of the x-axis andy-axis. At the time of detecting touches, a scanning method is used inorder to sequentially scan the x-axis and y-axis. In addition, the touchdetection may be performed after the entire x-axis is made to be in anactive state, or after the entire y-axis is made to be in an activestate. Even in the case of this configuration, a detection techniqueusing a voltage difference is applied in the same manner as theabove-described dot matrix method.

Meanwhile, in the embodiment having a linear array of FIG. 18, referringto the Equations 1 and 2 to detect the voltage difference, theresistance values of the linear patterns 10 and the sensor signal lines22 are not included in the variables. Accordingly, the transparentmaterial such as ITO or IZO having a relatively larger resistance valuemay be used for the linear patterns 10 and the sensor signal lines 22.As a result, it is possible to manufacture the linear patterns 10 andthe sensor signal lines 22 with a single mask.

On the other hand, FIG. 19 illustrates a configuration of a thin filmtransistor (TFT) substrate for a liquid crystal display (LCD), andparticularly, shows the configuration of the TFT substrate of atransverse electric field mode. In contrast to the aforementionedembodiment, the common electrode 220 is formed only in part of the areaof the panel in the LCD of the transverse electric field mode. Referringto FIG. 19, the LCD of the transverse electric field mode will bedescribed below briefly.

As illustrated in FIG. 19, gate lines 242 and data lines 244 arearranged in the length and breadth on the upper surface of the TFTsubstrate, and areas that are sectionalized by the gate lines 242 andthe data lines 244 form pixels. A TFT 250 for switching an image signalis mounted in a pixel. A gate electrode 251 of the TFT 250 is connectedto a gate line 242 to receive a scanning signal, and a source electrode253 and a drain electrode 255 thereof are connected to a data line 244and a pixel electrode line 248, respectively. In addition, asemiconductor layer 257 of the TFT 250 forms a channel between thesource electrode 253 and the drain electrode 255 in order to apply animage signal to a liquid crystal layer. As shown, a common electrodeline 246 is formed in the pixel in parallel to the pixel electrode line248.

In the LCD having such a configuration, if the TFT 250 is activated, andthus an image signal is applied to the pixel electrode line 248, asubstantially parallel transverse electric field occurs between thecommon electrode line 246 and the pixel electrode line 248, and theliquid crystal molecules move on a plane.

However, as shown, the common electrode line 246 is formed in only apartial area. Thus, Cvcom that is formed between the sensor pattern 10and the common electrode line 246 is formed smaller than in the previousembodiment. Since Cvcom is proportional to the opposite area between thesensor pattern 10 and the common electrode line 246, the opposite areais formed by an area formed by the common electrode line 246, eventhough the sensor pattern 10 covers the entire pixel shown in FIG. 18.If the common electrode 220 of the display device 200 in the embodimentof FIG. 18 is formed as shown in FIG. 19, Cvcom with respect to Ct willbe very small in size. Thus, the size of the voltage difference due tooccurrence or non-occurrence of a touch input becomes larger.

However, in the embodiment of FIG. 19, parasitic capacitances Cp due tothe gate lines 242, the data lines 244, and the pixel electrode lines248 may have values that are approximate to Cvcom or higher values thanCvcom. The parasitic capacitances Cp may serve as noise components forthe touch signal detection. Thus, in the embodiment of FIG. 19, it isdesirable that the drive IC 30 detects the touch by considering thetiming when there are no changes in the signals in the gate lines 242and the data lines 244 of the LCD.

FIGS. 20 and 21 are a cross-sectional view and an exploded perspectiveview of a display device with a built-in touch-screen panel,respectively. Referring to FIGS. 20 and 21, the touch screen panel andthe display device with the built-in touch-screen panel according to thepresent invention will be described below.

As shown in FIG. 20, the color filter 215 of the display device 200 maybe replaced with a touch-screen panel according to the presentinvention. In the same manner as in a conventional LCD, the commonelectrode 20 is formed on the lower surface of the color filter 215. Asanother example, in a transverse electric field mode such as that ofFIG. 19, the common electrode 220 is formed on the upper surface of theTFT substrate 205. In the example of FIG. 19 or 20, as shown, the sensorpatterns 10 are formed on the color filter 215. In addition, aprotection panel 52 such as reinforced glass may be mounted on the uppersurface of the sensor patterns 10, in order to protect the sensorpatterns 10. In the embodiment of FIG. 20, the protective panel 52 isattached on the upper surface of the color filter 215 by means of atransparent adhesive material such as a UV-curable resin 98.

In this configuration, only the color filter 215 exists as a mediumbetween the sensor patterns 10 and the common electrode 220. Thus, Cvcombecomes large, and Ct becomes relatively small. The growth of Cvcommeans that the influence of Cp can be minimized as shown in theEquation 1. Thus, a touch signal can be obtained more stably byminimizing the influence of Cp due to the unknown factors.

In the illustrated example, a drive IC 60 for displaying images on a LCDis mounted in the form of a COG pattern on the TFT substrate 205. Adrive IC 30 for controlling a touch signal is mounted in the form of aCOG or COF pattern on the color filter 215. FPCs 96 and 97 are withdrawnfrom the drive ICs 30 and 60, respectively. Further, the touch drive IC30 and the LCD drive IC 60 may be integrated into a single IC. Inaddition, the TFT substrate 205 and the color filter 215 are connectedto the FPCs so as to transmit and receive signals externally.

Meanwhile, if the sensor patterns 10 and the sensor signal lines 22according to the present invention may be manufactured by using a singlemask, the yield is increased and the manufacturing time is reduced, tothus reduce manufacturing costs. Such a method of manufacturing thesensor patterns 10 and the sensor signal lines 22 with a single maskwill follow with reference to FIG. 22.

In the case of forming the sensor patterns 10 on the top surface of thecolor filter 215 as shown in FIG. 20 or 21, resins representing a senseof color exist in the form of Red, Green and Blue (R/G/B) on the otherside of one surface of the color filter 215 on which the sensor patterns10 are patterned, in which the Red, Green and Blue resins are defined aspixels, and a combination of three pixels 270 a, 270 b, and 270 c ofR/G/B is defined as a dot 270, as shown in FIG. 22.

FIG. 22 illustrates the color filter 215 consisting of six dots 270 inthe horizontal direction and five dots 270 in the vertical direction. Asshown in FIG. 22, the sensor patterns 10 may be located at a BlackMatrix (BM) 275 that is a boundary portion of the respective pixels 270a, 270 b, and 270 c.

The BM 275 plays a role of hiding signal lines connected to therespective pixels 270 a, 270 b, and 270 c of the LCD, or distinguishingsenses of color of the pixels, and are usually placed in a width ofseveral μm to several tens μm. The BM 275 consists of a material of ablack color group that is not reflected and that is not permeable, andis located at the boundary surface of the resin at the lower side of thecolor filter. A share of the BM 275 in one pixel 270 a, 270 b, or 270 cis usually around 20% to 50%. Thus, although the sensor patterns 10 areformed on the BM 275, a sufficient area of the sensor patterns can besecured.

Referring to FIG. 22, the sensor patterns 10 are located in the BMbetween the pixels and one of the sensor patterns 10 is formed toaccommodate four dots 270. The sensor patterns 10 are all connected toeach other in a grid structure, within the BM 275 around the pixels 270a, 270 b, and 270 c and the dots 270, and the sensor signal lines 22 arewired to the BM to be connected to the drive IC 30.

According to the advantages of this structure, the sensor patterns 10and the sensor signal lines 22 may be disposed in the BM 275 that is inan invisible region, and the sensor patterns 10 and the sensor signallines 22 may be formed of metal. Thus, the sensor patterns 10 and thesensor signal lines 22 may be formed with a single mask. Of course, theresistance values of the sensor signal lines 22 can be reduced and thusthere is no need to greatly consider the wiring resistance. In addition,although the sensor patterns 10 and the sensor signal lines 22 areformed of metal, an aperture ratio of the pixel does not degrade. Sincean electrical conductivity of metal is excellent, it is possible totransfer a more stable signal to the drive IC.

In the FIG. 22 embodiment, a plurality of pixels that do not contain thesensor patterns 10 are required between the sensor patterns 10 to wirethe sensor signal lines 22. In addition, in the illustrated example, theboundary interfaces of the sensor patterns 10 in the vertical directionare separated by a single pixel, but may be separated by a plurality ofpixels.

In the embodiment of FIG. 22, the sensor patterns 10 have been describedwith respect to the case that the sensor patterns 10 are mounted on theupper surface of the color filter, that is, on the outside of the colorfilter, but may exist in the inside of the color filter, that is,between color resins R/G/B and the inside of the color filter. When thesensor patterns are located on the upper side of the color filter, themanufacturing process of the color filter takes place in two locationsof the inside and outside of the glass, but when the sensor patterns arelocated at the inside of the color filter, the manufacturing process isexecuted only in the inside of the glass, to thereby simplify themanufacturing process and increase the yield.

In the case that a non-transmissive material such as metal is used,non-reflective metal is used, or non-reflective chrome oxide or silveroxide or an inorganic material or an organic material of a black colorgroup may be coated on the top surface of metal. The example of usingmetal has been described in this embodiment, but materials that are usedto form the sensor patterns and the signal lines are not limited tonon-transmissive materials such as metal, but materials havingconductivity such as transparent conductive materials may be alsoapplied.

In such an embodiment, the share of the BM is several tens %, and thusthe area of the sensor patterns 10 that are mounted on the BM is severaltens % of the area of the pixels. In addition, since the capacitanceformed in the Equation 4 becomes several tens %, touch detection is notobstructed by adjusting these absolute areas as desired.

According to another advantage of the FIG. 22 embodiment, since nosubstances exist in the transmissive area of pixels, transmittance ofpixels rises up when compared to other existing touch screens. Inaddition, in the case of the touch screen forming the sensor patternsmade of a conventional transparent conductive material, index matchingis executed in order to prevent visual identification of the transparentconductive material. The FIG. 22 embodiment has the advantage ofremoving such an index matching process.

In the embodiment of FIG. 22, the case where dots are 6×5 (width×length)has been described, but the present invention is not limited thereto.That is, dots of several tens to several hundreds, or the numberexceeding several hundreds may be located on the lower side of a singlesensor pattern 10. Also, in this example, the case where dots areseparated through the color filter has been described, but the technicalspirit of the present embodiments may be applied to all cases havingseparators that separate pixels from each other, such as an example withno color filter but with separators separating between pixels bybulkheads like a plasma display panel (PDP).

However, the present invention is not limited to the above embodiments,and it is possible for one who has an ordinary skill in the art to makevarious substitutions, modifications and variations without departingoff the spirit of the invention defined by the claims.

[Description of reference numerals] 10: sensor patterns 10a: x-axislinear sensor patterns 10b: y-axis linear sensor patterns 12: chargingunit 14: touch detection sensor 14a: ADC 18: amplifier 18a: differentialamplifier 19: comparator 22: sensor signal lines 22a: transparent signallines 22b: metal signal lines 25: finger 28: memory unit 30: drive IC30a: master drive IC 30b: slave drive IC 31: driver 33: timingcontroller 35: signal processor 37: alternating voltage generator 40:CPU 41a: opposite areas 41b: connectors 42: crossing portions 43: commonvoltage detector 45: common voltage information 47: selector receiver50: substrate 52: protection panel 57: adhesive material 58: air gap 59:connectors 60: drive ICs 90: active region 92: invisible region 94:communication channel 96: FPC 97: FPC 98: UV-curing resin 200: displaydevice 205: TFT substrate 210: liquid crystal layer 215: color filter220: common electrode 230: sealants 242: gate lines 244: data lines 246:common electrode lines 248: pixel electrode lines 250: TFT 251: gateelectrode 253: source electrode 255: drain electrode 257: semiconductorlayer 270: dots 275: BM (Black Matrix)

1. A capacitive touch screen panel for detecting occurrence of a touchcapacitance (Ct) by an approach of a bodily finger (25) or a touch inputinstrument such as a conductor similar to the bodily finger, thecapacitive touch screen panel comprising: a substrate (50); at least onesensor pattern (10) that is formed on top of the substrate (50), andforms the touch capacitance (Ct) between the touch input instrument andthe sensor pattern; an auxiliary capacitor (Caux) whose one side isconnected to the sensor pattern (10) and to the other side of which adriving voltage for detection of a touch input is applied; a touchdetection sensor (14) that is connected to the sensor pattern (10), andthat detects a voltage difference that is a difference in the magnitudeof a voltage generated in the sensor pattern (10) by a driving voltageapplied to the auxiliary capacitor (Caux) when the touch capacitance(Ct) is added at the time of occurrence of a touch input, in comparisonwith the magnitude of a voltage generated by a driving voltage appliedto the auxiliary capacitor (Caux) in the sensor pattern (10) at the timeof non-occurrence of a touch input, to thereby detect a touch signal;and a drive integrated circuit (IC) (30) that controls the charging unit(12) to supply a pre-charge signal to the touch capacitance (Ct) andcomputes touch coordinates from the output of the touch detection sensor(14), wherein the driving voltage that is applied to the other side ofthe auxiliary capacitor (Caux) is an alternating voltage that alternatesat a predetermined frequency.